WHAT ABOUT HER MAKES YOU LIKE THIS

this is making me so angry.I despise cheating above all. everything was great. His wife is good at him. He is good at his wife. But why isn't it enough? why he has to ruin everything? he is not without conscious. He knows what he is doing BUT he is still doing it. It's the worst.It makes the wife confused more. Should she despise her husband? or should she blame the mistress? or herself?