I am young but I feel strongly about this issue so I will add my adolescense input. I feel infedility can be physical or mental. I understand that it's only natural for people to look and check out other people but when they do what I call a "double-take" is when you have to worry. I agree with the look but not touch thing but I feel the woman or man you married should be the most amazing person in your eyes, physically and mentally and when you find someone else more intriguing than your mate, I feel that's infedility in itself. And ofcourse if you so much as kiss someone else yeah yeah yeah that's infedility also but on a different level. I'm sorry if this doesn't make sense, I usually only understand what I write