Why are people so uptight about pre-marital sex?
If I commit adultery & repent, must my spouse take me back?
Was Jesus tempted to have sex?
The Bible teaches that sex is a part of marriage. Sex before or outside of marriage is fornication, a sin. God ask that we be "holy as He is holy". Paul in Romans exhorts that we not let sin have dominion over our "members". Even in the Old Testament God commands that we not "covet", whether it be things, or "another man's wife".
If a person commits a sin & asks for forgiveness, that responsibility is mandated by God when repentence occurs. Peter asked Jesus how often he should forgive & Jesus said as often as a repentent brother asks. There is the obligation for the spouse to do so also, but they may still proceed toward a divorce; one would hope that the mercy & forgiveness taught by Christ would prevail, however.
The scriptures say that Jesus was tempted in all ways like as we , "yet without sin". This means that the temptation was certainly present (women were always around Him), but did not overtake Him.