Baha'u'llah and Abdu’l-Bahá on sex, marriage and divorce.

He is My true follower who, if he come to a valley of pure gold, will pass straight through it aloof as a cloud, and will neither turn back, nor pause. Such a man is, assuredly, of Me. From his garment the Concourse on high can inhale the fragrance of sanctity.... And if he met the fairest and most comely of women, he would not feel his heart seduced by the least shadow of desire for her beauty. Such an one, indeed, is the creation of spotless chastity"(Baha'u'llah, Gleanings from the Writings of Baha'u'llah, p. 118)

"Say: O concourse of monks! Enter ye into wedlock, that after you another may arise in your stead. We, verily, have forbidden you lechery, and not that which is conducive to fidelity."
(Baha'u'llah, Epistle to the Son of the Wolf, p. 49)

“Ye are forbidden to commit adultery, sodomy and lechery. Avoid them, O concourse of the faithful,” Bahá’u’lláh.

"It is forbidden you to wed your fathers' wives. We shrink, for very shame, from treating of the subject of boys. Fear ye the Merciful, O peoples of the world! Commit not that which is forbidden you in Our Holy Tablet, and be not of those who rove distractedly in the wilderness of their desires." (Baha'u'llah, The Kitab-i-Aqdas, p. 58)

And when He desired to manifest grace and beneficence to men, and to set the world in order, He revealed observances and created laws; among them He established the law of marriage, made it as a fortress for well-being and salvation, and enjoined it upon us in that which was sent down out of the heaven of sanctity in His Most Holy Book.

God hath prescribed matrimony unto you...Enter into wedlock, O people, that ye may bring forth one who will make mention of Me amid My servants. This is My bidding unto you; hold fast to it as an assistance to yourselves.

Abdu’l-Bahá has stated the following in this regard: Bahá’í marriage is the commitment of the two parties one to the other, and their mutual attachment of mind and heart. Each must, however, exercise the utmost care to become thoroughly acquainted with the character of the other, that the binding covenant between them may be a tie that will endure forever. Their purpose must be this: To become loving companions and comrades and at one with each other for time and eternity.

The true marriage of Bahá’ís is this, that husband and wife should be united both physically and spiritually, that they may ever improve the spiritual life of each other, and may enjoy everlasting unity throughout all the worlds of God. This is Bahá’í marriage.
In another Tablet, He has written:

O ye two believers in God! The Lord, peerless is He, hath made woman and man to abide with each other in the closest companionship, and to be even as a single soul. They are two helpmates, two intimate friends, who should be concerned about the welfare of each other.
If they live thus, they will pass through this world with perfect contentment, bliss, and peace of heart, and become the object of divine grace and favor in the Kingdom of heaven. But if they do other than this, they will live out their lives in great bitterness, longing at every moment for death, and will be shamefaced in the heavenly realm. Strive, then, to abide, heart and soul, with each other as two doves in the nest, for this is to be blessed in both worlds.

As for the question regarding marriage under the Law of God: First thou must choose one who is pleasing to thee, and then the matter is subject to the consent of father and mother. Before thou make thy choice, they have no right to interfere.

Should resentment or antipathy arise between husband and wife, he is not to divorce her but to bide in patience throughout the course of one whole year, that perchance the fragrance of affection may be renewed between them. If, upon the completion of this period, their love hath not returned, it is permissible for divorce to take place.

Bahá’u’lláh, The Kitab-i-Aqdas, p. 43

https://www.bahai.org/beliefs/life-spirit/character-conduct/articles-resources/compilation-family-life-marriage

Some symbols from the holy scriptures explained by Baháʼu'lláh and Abdu'l-Bahá.

Fire: Gods love. https://bahai-library.com/compilation_fire_symbol

Hellfire: "Do not associate with the wicked, because the company of the wicked change the light of life into the fire of remorse. 

Heaven and hell: Think ye of love and good fellowship as the delights of heaven, think ye of hostility and hatred as the torments of hell. Where is Paradise, and where is Hell? Say: 'The one is reunion with Me; the other thine own self. There is no fiercer hell, no more fiery abyss, than to possess a character that is evil and unsound; no more darksome pit nor loathsome torment than to show forth qualities which deserve to be condemned.

The meaning of Jesus dying for our sins is this: Christ sacrificed Himself so that mankind might be freed from the imperfections of the material nature and endowed with the virtues of the spiritual nature. Abdul Baha Know thou that when the Son of Man [Christ] yielded up His breath to God, the whole creation wept with a great weeping. By sacrificing Himself, however, a fresh capacity was infused into all created things. We testify that when He came into the world, He shed the splendor of His glory upon all created things. He it is who purified the world. Blessed is the man who, with a face beaming with light, hath turned towards Him. 

Beasts: Baha’is believe the biblical beasts are allegorical descriptions of the organized forces that always oppose new revelations. Symbolically, the first beast refers to the armies that opposed Muhammad. 

Life and death: By the terms 'life' and 'death,' spoken of in the scriptures, is intended the life of faith and the death of unbelief. His Holiness Jesus Christ has pronounced that those who have not received a portion of the divine spirit are dead. The wages of sin is death." Romans 6:23 Wherever in the holy books they speak of raising the dead, the meaning is that the dead were blessed by eternal life. 

Only the believers in the Prophet Noah were spiritually alive, safely preserved in the "ark" of His Faith, and the other people on the earth were spiritually dead. By this bread is meant the heavenly sustenance of divine perfections. In other words, whoso partakes of this sustenance—that is, whoso acquires the outpouring grace of God, draws illumination from His light, and obtains his portion of the perfections of Christ—will attain everlasting life. What is meant by blood, likewise, is the spirit of life, which consists in divine perfections, heavenly splendours, and eternal grace.

Water: The knowledge of God; life. But the heavenly water and spirit, which are knowledge and life, make the human heart good and pure; the heart which receives a portion of the bounty of the Spirit becomes sanctified, good and pure -- that is to say, the reality of man becomes purified and sanctified from the impurities of the world of nature. Water is the cause of life, and when Christ speaks of water, He is symbolizing that which is the cause of Everlasting Life. This life-giving water of which He speaks is like unto fire, for it is none other than the Love of God, and this love means life to our souls.

Grave/tomb: Heedlessness and error. Behold, all the people are imprisoned within the tomb of self, and lie buried beneath the nethermost depths of worldly desire! 

Leprosy: Through Him the leper recovered from the leprosy of perversity and ignorance. Leprosy may be interpreted as any veil that intervene between man and the recognition of the Lord, his God. 

Angels: People who have replaced faults with divine attributes. Those who, reinforced by the power of the spirit, have consumed, with the fire of the love of God, all human traits and limitations, and have clothed themselves with the attributes of the most exalted Beings and of the Cherubim. The meaning of ‘angels’ is the confirmations of God and His celestial powers. Likewise angels are blessed beings who have severed all ties with this nether world, have been released from the chains of self and the desires of the flesh, and anchored their hearts to the heavenly realms of the Lord. These are of the Kingdom, heavenly; these are of God, spiritual; these are revealers of God’s abounding grace; these are dawning-points of His spiritual bestowals. 

Adam and Eve: Adam signifies the heavenly spirit of Adam, and Eve His human soul. For in some passages in the Holy Books where women are mentioned, they represent the soul of man. 

The tree of good and evil signifies the human world; for the spiritual and divine world is purely good and absolutely luminous, but in the human world light and darkness, good and evil, exist as opposite conditions.  

Serpent: The meaning of the serpent is attachment to the human world. This attachment of the spirit to the human world led the soul and spirit of Adam from the world of freedom to the world of bondage and caused Him to turn from the Kingdom of Unity to the human world. When the soul and spirit of Adam entered the human world, He came out from the paradise of freedom and fell into the world of bondage. From the height of purity and absolute goodness, He entered into the world of good and evil. The tree of life is the highest degree of the world of existence: The position of the Word of God, and the supreme Manifestation. 

-If there is a symbol you don't find here, but you would like to see the meaning of, please write in the comment below and I will try to provide.-

Abdu’l-Bahá words about preparing for the life beyond

 

In this world he must prepare himself for the life beyond. That which he needs in the world of the Kingdom must be obtained here. Just as he prepared himself in the world of the matrix by acquiring forces necessary in this sphere of existence, so likewise the indispensable forces of the divine existence must be potentially attained in this world.

What is he in need of in the Kingdom which transcends the life and limitation of this mortal sphere? That world beyond is a world of sanctity and radiance; therefore it is necessary that in this world he should acquire these divine attributes. In that world there is need of spirituality, faith, assurance, the knowledge and love of God. These he must attain in this world so that after his ascension from the earthly to the heavenly Kingdom he shall find all that is needful in that life eternal ready for him.

That divine world is manifestly a world of lights; therefore man has need of illumination here. That is a world of love; the love of God is essential. It is a world of perfections; virtues or perfections must be acquired. That world is vivified by the breaths of the Holy Spirit; in this world we must seek them. That is the Kingdom of life everlasting; it must be attained during this vanishing existence.

By what means can man acquire these things? How shall he obtain these merciful gifts and powers? First, through the knowledge of God. Second, through the love of God. Third, through faith. Fourth, through philanthropic deeds. Fifth, through self-sacrifice. Sixth, through severance from this world. Seventh, through sanctity and holiness. Unless he acquires these forces and attains to these requirements he will surely be deprived of the life that is eternal. But if he possesses the knowledge of God, becomes ignited through the fire of the love of God, witnesses the great and mighty signs of the Kingdom, becomes the cause of love among mankind, and lives in the utmost state of sanctity and holiness, he shall surely attain to second birth, be baptized by the Holy Spirit and enjoy everlasting existence.

Is it not astonishing that although man has been created for the knowledge and love of God, for the virtues of the human world, for spirituality, heavenly illumination and life eternal, nevertheless he continues ignorant and negligent of all this? Consider how he seeks knowledge of everything except knowledge of God. For instance, his utmost desire is to penetrate the mysteries of the lowest strata of the earth. Day by day he strives to know what can be found ten metres below the surface, what he can discover within the stone, what he can learn by archaeological research in the dust. He puts forth arduous labors to fathom terrestrial mysteries but is not at all concerned about knowing the mysteries of the Kingdom, traversing the illimitable fields of the eternal world, becoming informed of the divine realities, discovering the secrets of God, attaining the knowledge of God, witnessing the splendors of the Sun of Truth and realizing the glories of everlasting life. He is unmindful and thoughtless of these. How much he is attracted to the mysteries of matter and how completely unaware he is of the mysteries of divinity! Nay, he is utterly negligent and oblivious of the secrets of divinity. How great his ignorance! How conducive to his degradation! It is as if a kind and loving father had provided a library of wonderful books for his son in order that he might be informed of the mysteries of creation; at the same time surrounding him with every means of comfort and enjoyment; but the son amuses himself with pebbles and playthings, neglectful of all his father’s gifts and provision. How ignorant and heedless is man! The Father has willed for him glory eternal and he is content with blindness and deprivation. The Father has built for him a royal palace but he is playing with the dust; prepared for him garments of silk but he prefers to remain unclothed; provided for him delicious foods and fruits while he seeks sustenance in the grasses of the field.

Praise be to God! you have heard the call of the Kingdom. Your eyes are opened; you have turned to God. Your purpose is the good-pleasure of God, the understanding of the mysteries of the heart and investigation of the realities. Day and night you must strive that you may attain to the significances of the heavenly kingdom, perceive the signs of divinity, acquire certainty of knowledge and realize that this world has a creator, a vivifier, a provider, an architect,—knowing this through proofs and evidences and not through susceptibilities,—nay, rather, through decisive arguments and real vision; that is to say, visualizing it as clearly as the outer eye beholds the sun. In this way may you behold the presence of God and attain to the knowledge of the holy, divine Manifestations. From the book Foundations of world unity https://reference.bahai.org/en/t/c/FWU/fwu-19.html#pg64