Okay, so let me present here probably the most common cheating scenario in the world. A couple married, then after having a child or two, the wife gained a ton of weight (biology?) and now wouldn't care to undo it by working it off or dieting it off. This is extremely unfair on the wife, even before going into the marriage/cheating question, but ... . Now, the husband is trying to adapt to the "new" wife, but like with every adaptation, there is a failure rate. So, as a result, some men fail emotionally, sending the marriage to instability, some men fail physically, sending the marriage into cheat. How high a % sould we call asshole-ishness, and how high a % should we call normal? Is it reasonable to call a 50+% ubnormal/assholish, or 40+%, or 30+%? (The national divorce rate is 50 %.)