Why does cheating seem like the only way now?

every relationship nowadays one of the two ALWAYS cheats. why do people cheat so much now? it used to be taboo and it is still wrong but people seem to have accepted the fact that their significant other is cheating? it doesnt make any sense to me. if someone could PLEASE help me understand why cheating seems to be considered 'okay' in society. all the girls ALWAYS take the guy back and vice versa.