Unrepentant adultery might lead to division of property, alimony and child support. There are also risks of paternity lawsuits and sexually transmitted disease from fornication and adultery.
Jesus advised against adultery:
Matthew 5 (WEB)
27 “You have heard that it was said, ‘You shall not commit adultery;’
Exodus 20:14 28 but I tell you that everyone who gazes at a woman to lust after her has committed adultery with her already in his heart. 29 If your right eye causes you to stumble, pluck it out and throw it away from you. For it is more profitable for you that one of your members should perish than for your whole body to be cast into Gehenna. 30 If your right hand causes you to stumble, cut it off, and throw it away from you. For it is more profitable for you that one of your members should perish, than for your whole body to be cast into Gehenna.
31 “It was also said, ‘Whoever shall put away his wife, let him give her a writing of divorce,’
Deuteronomy 24:1 32 but I tell you that whoever puts away his wife, except for the cause of sexual immorality, makes her an adulteress; and whoever marries her when she is put away commits adultery.