Are people who get married young more likely to cheat later?

Why does it matter if someone cheats? the and are simply limbs, just like hands. so why would most people get angry when their mate has with someone but not when they shake hands. the and are simply touching, just like the hands are when shaking hands. the only actual difference is that the can send sperm into the female, leading to life. but if the male uses a condom no baby will be born, making it exactly like shaking hands or any other common physical contanct. Why do people feel betrayed when their partner has with someone else but them? is it greed, maybe they just want the person all to themselves because they are greedy? A person having an affair simply wants pleasure, what is so wrong with that? is it wrong for someone to enjoy themselves with someone other than their mate? i think there is no reason to get angry if your mate has protected with another person.