When I was a young man I would listen to Dr Joyce Brothers each day during my commute to work. In one segment she talked about wives of sailors cheating while the husband was out to sea. The final conclusions of the study was that the ones who cheated would cheat, no matter if the husband trusted them or not. The ones that did not cheat had a strong desire to be faithful. Basically, cheaters would cheat and non-cheaters would not. Had nothing to do with loneliness, emotions, lack of fulfillment, etc..........those were rationalizations.
I have talked with many people over the years, both male and female. I totally agree with the Dr Joyce Brothers study. Certainly borne out by my conversations with these folks.