Original sin had terrible consequences even in regards to marriage (bold CCC and Scripture below mine).
CCC 1607 According to faith the disorder we notice so painfully does not stem from the nature of man and woman, nor from the nature of their relations, but from sin. As a break with God, the first sin had for its first consequence the rupture of the original communion between man and woman. Their relations were distorted by mutual recriminations; their mutual attraction, the Creator’s own gift, changed into a relationship of domination and lust; and the beautiful vocation of man and woman to be fruitful, multiply, and subdue the earth was burdened by the pain of childbirth and the toil of work.
Divorce was permitted for “hardness of heart” (without the graces of Jesus work, if men couldn’t get a new wife, until the first one died, what do you think would have happened to many wives?).
In the New Covenant, Jesus elevates marriage back to what was always intended which was broken by original sin. This means Jesus also gives us the graces for such.
CCC 2382 The Lord Jesus insisted on the original intention of the Creator who willed that marriage be indissoluble.174 He abrogates the accommodations that had slipped into the old Law.175
Between the baptized, "a ratified and consummated marriage cannot be dissolved by any human power or for any reason other than death."176
MATTHEW 19:8 8 He said to them, "For your hardness of heart Moses allowed you to divorce your wives, but from the beginning it was not so.
Marriage is a Sacrament and is thus indissoluble.
In the context of marriage, this means just what Jesus said it did two verses earlier: “what God has brought together, let no man put asunder”.
MATTHEW 19:6 6 So they are no longer two but one. What therefore God has joined together, let not man put asunder."
In other words, man cannot break the marital bond. Only God can do that. He does that when we die.
That’s why in Heaven no one will be married or given in marriage (Matthew 22:30, Mark 12:25).
(I am not saying there isn’t something special in Heaven when a husband and wife are both in Heaven. It just won’t be earthly marriage)
But upon this earth, the marital bond is indissoluble among Christians.
The people desiring intimate relations with different people MUST come up with reasons to rationalize this behavior. But you won’t find Christian divorce and re-marriage taught in the New Covenant sense . . . except by the Protestant “fathers” (Read the Church Fathers then go read “Table Talk” and ask yourself who you think teaches classic authentic Christianity.).
The deniers of this will show you verses that talk of divorce. But his does NOT break the marital bond.
Ask them where it talks of divorce and RE-MARRIAGE in the New Covenant sense.
Even Matthew 5:32 asserts against divorce and re-marriage (all caps mine):
MATTHEW 5:32a 32 But I say to you that every one who divorces his wife, except on the ground of unchastity, makes her an adulteress; AND . . . .
OK. St. Matthew talks of divorcing here. But what about re-marriage? Fortunately he tells us in the very next words.
MATTHEW 5:32b . . . . AND whoever marries a divorced woman commits adultery.
The whole verse. . . . .
MATTHEW 5:32 32 But I say to you that every one who divorces his wife, except on the ground of unchastity, makes her an adulteress; and whoever marries a divorced woman commits adultery.
The early Church saw it this way too.
ST. JEROME “Wherever there is fornication and a suspicion of fornication a wife is freely dismissed. Because it is always possible that someone may calumniate the innocent and, for the sake of a second joining in marriage, act in criminal fashion against the first,
it is commanded that when the first wife is dismissed a second may not be taken while the first lives.”
St. Jerome. Commentaries on Matthew. 3:19:9 A.D. 398.
ST. JUSTIN THE MARTYR “In regard to chastity, (Jesus) has this to say:
‘If anyone look with lust at a woman, he has already before God committed adultery in his heart.’ And, ‘Whoever marries a woman who has been divorced from another husband,
commits adultery.’ According to our Teacher, just as they are sinners who contract a second marriage, even though it be in accord with human law, so also are they sinners who look with lustful desire at a woman.
He repudiates not only one who actually commits adultery, but even one who wishes to do so; for not only our actions are manifest to God, but even our thoughts”
- St. Justin the Martyr. First Apology 15 A.D. 148:155.
ST. CLEMENT OF ALEXANDRIA "That Scripture counsels marriage, however, and never allows any release from the union, is expressly contained in the law: ‘You shall not divorce a wife, except for reason of immorality.’ And it regards as adultery the marriage of a spouse, while the one from whom a separation was made is still alive. ‘Whoever takes a divorced woman as wife commits adultery,’
- St. Clement of Alexandria. Stromatesis 2:23:145:3 (post A.D. 202).
ORIGEN “Just as a woman is an adulteress, even though she seem to be married to a man, while a former husband yet lives, so also the man who seems to marry her who has been divorced does not marry her, but, according to the declaration of our Savior, he commits adultery with her”
- Origen Commentaries on Matthew. 14:24 A.D. 244.