There are many. The one that got cheated on sometimes feels that is something they did or did not do to keep the cheater from straying. They look to some personal trait, too. It usually isn't any of those. The cheater is the one that wasnt having the respect enough for this person to be mature enough to say something before the action took place. If your that unhappy in a relationship have respect for yourself and others to do the right thing. The cheater usually doesnt feel bad or guilty unless they get caught. They justify what they did by blaming the other person. The effect they feel is "well, I'll just move on to the next, she/he wasnt worth is anyway" total denial of irresponsibility. If there are children involved sometimes they blame themselves and withdraw because no their parents are separating and they think they could have done something different. It basically comes down to a selfish person thinking their feelings are more important then those they chose to committ to and when it doesnt go their way they fill a void that could have easily been taken care of with someone else and they think its ok. Cheaters rarely change because its actually something they are lacking within that makes them so self absorbed and umcompassionate of others.
cheaters do feel guilty, actually. The guilt they feel transcribes into suspicions of the other person (the person who was cheated on). they come to the subconcious conclusion "if i can do it so can they" and they now are suspicious that they are infact being cheated on. it is basic psychology that you learn in highschool.