These passages get read at weddings, printed on invitations, and then left there. Each one asks something specific of the two people standing at the front.
All quotations are from the King James Version, which is in the public domain. If your church reads from a Malayalam or Tamil translation, the wording will differ and the obligation will not.
Leaving, before cleaving
Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh. Genesis 2:24, King James Version
The leaving comes first in the sentence, and it is the part we handle worst. In a joint household nobody is moving out, so the leaving has to happen in another way: the husband's first loyalty shifts. When his mother and his wife disagree, he is no longer a son deciding between two women. He is a husband who has been told where he stands.
This is not disrespect towards parents. Honouring your father and mother is a commandment and it does not expire at the wedding. But a man who runs every decision past his mother for the next thirty years has not left, and his wife will know it by the second month.
What is asked of a husband
Husbands, love your wives, even as Christ also loved the church, and gave himself for it. Ephesians 5:25, King James Version
This verse is quoted far less often than the one about wives three lines earlier, which tells you something about who is doing the quoting. The standard set here is death. Christ did not lead the church by insisting on his position. He washed feet and then he was crucified.
In an ordinary week that looks like taking the night feed, carrying your own plate, and defending your wife's name in a room where she is not present. A husband who cites headship while his wife carries the entire house has read half a sentence.
Husbands, love your wives, and be not bitter against them. Colossians 3:19, King James Version
Bitterness is the specific sin named here, and it is a quiet one. It is the sarcasm in front of guests, and the grudge kept from four years ago and produced during an argument about something else.
Living with knowledge
Likewise, ye husbands, dwell with them according to knowledge, giving honour unto the wife, as unto the weaker vessel, and as being heirs together of the grace of life; that your prayers be not hindered. 1 Peter 3:7, King James Version
"According to knowledge" means learn her. Know what frightens her, what her work is actually like, which of her relatives wound her. Marriage here is a thing you study.
Then notice the warning at the end. Peter says a husband who treats his wife badly will find his prayers hindered. How you behave at home affects your standing before God. That is a heavier claim than most sermons on this passage admit.
What love does, in verbs
Charity suffereth long, and is kind; charity envieth not; charity vaunteth not itself, is not puffed up, doth not behave itself unseemly, seeketh not her own, is not easily provoked, thinketh no evil. 1 Corinthians 13:4-5, King James Version
Paul defines love almost entirely as things you do and refuse to do. There is no feeling in the list. "Seeketh not her own" is the one that decides most arguments in a marriage, because most arguments are two people each seeking their own and calling it fairness.
"Is not easily provoked" is worth sitting with if you have a temper. Scripture treats a short fuse as a failure of love, not a personality trait to be managed by everyone around you.
Two, and a third
Two are better than one; because they have a good reward for their labour. For if they fall, the one will lift up his fellow: but woe to him that is alone when he falleth; for he hath not another to help him up. And if one prevail against him, two shall withstand him; and a threefold cord is not quickly broken. Ecclesiastes 4:9-12, King James Version
This is the passage for the hard years, not the wedding day. It assumes falling. It assumes being overpowered. The promise is not that trouble will stay away but that it will meet two of you.
The threefold cord is usually explained from the pulpit as husband, wife and God, and that reading has held up well for a long time. Practically: a couple who pray together have somewhere to take an argument other than their own stubbornness.
Respect, and why it is commanded
Nevertheless let every one of you in particular so love his wife even as himself; and the wife see that she reverence her husband. Ephesians 5:33, King James Version
Paul commands respect, which tells you it is not automatic and does not depend on feeling. A wife is asked to speak about her husband, to him and about him, in a way that builds him. Contempt in front of the children does damage that apologies do not undo.
The verse binds both sides in one sentence. Neither half was given as a tool for correcting the other.
On permanence
What therefore God hath joined together, let not man put asunder. Mark 10:9, King James Version
Our Lord's words, and every Indian church takes them seriously, though they differ on what follows when a marriage has already ended. A Catholic parish will speak to you about annulment. Many Protestant and Pentecostal churches will receive a divorced member and conduct a second marriage. If this touches your family, ask your own priest or pastor rather than an argument on the internet.
Read before a wedding, the verse is a warning against treating marriage as reversible. It is addressed to the couple, and to every relative who might later work to pull them apart.
If you read only one at the wedding
Take Ephesians 5:25. Everything difficult in a marriage becomes simpler when the person with more power in the room has already agreed to spend it on the other.