I think when people didn't getproper attention to the one who wanted to spend whole life with you .there the people cheat

Personally I think it's about insecurity as well. I know someone who cheated because they thought they were cheated on which just oozes insecurity. All in all I think all forms of cheating ultimately expresses insecurity.

I think the best thing to do when one gets cheated on is just be thankful. They made the decision easy.

One should never compromise about cheating. Once it happens the relationship is dead and not worth pursuing anymore since the trust is gone and will never fully heal, no matter what course is taken.

Just another chapter in the book that ended which means a new one begins! It'll hurt for a while of course, the betrayal that is.
But it will never be the end of the world.

Either they don't believe they are good enough for the relationship or they don't value what they have.