How Can People Hurt Someone Like That

I think that people who cheat are stupid. That might sound harsh but really what is the point of cheating on someone. If you are that unhappy with a person than why not just leave them. I think that leaving someone would hurt someone less that cheating on them and them finding out about it. I just think that its hurtful and that the person cheating would feel upset and angry if it was the other way around so why make someone feel that way. I guess I may just be strongly opinionated on the subject but I strongly believe that if you are that unhappy with someone that you feel the need to cheat on them than just leave them. There is just no point in it I have told my friends the same thing when they told me about cheating on their significant other. They just look at me like I am stupid or they say that they love their significant other. Well if you loved them as much as you say you do that you would not cheat on them or think about cheating on them.