the christian rules about sex? why? , page-7

what about these?

If a man takes a wife and, after sleeping with her, dislikes her and slanders her and gives her a bad name, saying, “I married this woman, but when I approached her, I did not find proof of her virginity,”...but [t]here is...proof of...virginity...the elders shall take the man and punish him. They shall fine him a hundred shekels of silver and give them to the young woman’s father, because this man has given an Israelite virgin a bad name. She shall continue to be his wife; he must not divorce her as long as he lives.Deuteronomy 22

Matthew 19:5
‘For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh’?
So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.”

Matthew 19:9
I tell you that anyone who divorces his wife, except for sexual immorality, and marries another woman commits adultery.”


what exactly is: (i) sexual immorality; (ii) adultery; & (iii) what rationale does your God disapprove of this things?

thanks