Why Am I Wired To Be A Cuckold (or whatever)?

I have given a lot of thought to this over the years and I am now convinced that it stems from my early relationships with girls.  In high school I dated several girls but I only had what I would consider 2 serious relationships.  One of these lasted about 8 months and the other about 1-1/2 years.  In both of these relationships my girlfriend cheated on me with another guy and in both cases I took them back.  I think it was this willingness to forgive their transgressions that eventually led me to actually feel turned on by thoughts of them being with another man.  I know this is a difficult line to draw and probably most cases where a person is cheated on this is rarely the outcome but for me I think this was it. 

My second long term girlfriend in my formative years (the one I had for over a year and a half) cheated on me on 2 occasions with different guys.  By cheating I mean she had sex with them not just kissing or holding hands or some other adolescent idea of cheating.  As far as I know it only happened 2 times but it could have been and most likely was more than that.  In each case I took her back even though it was a hit to my ego and reputation.  What was even more odd was I never actually had sex with either of my girlfriends that cheated on me.  Go ahead call me a loser but I was too much of a nice guy I guess that I always stopped short of going all the way with girls as far as full intercourse is concerned.  It's not that I was some loser or goon on the contrary I was and still am a good looking outgoing guy that most people would assume has been laid his fair share of times but I'll just admit it now I was a virgin until I met my wife.  I am sure now that the reason she probably dumped me for good was because I was too nice or possibly too scared to go all the way with her.  Like a lot of guys I have always felt a little inadequate in the package department and that coupled with my nice guy demeanor made sex a very intimidating thing for me.  For a long time after our break-up, and really all the way until I met my now wife, when I masturbated I fantasized about this girl but in my fantasies it was not me having sex with her but one of the guys she was cheating on me with.  Deep I know!. 

I guess when I finally met my wife and I knew she was going to be the one this fantasy in my head morphed to where I replaced my ex-girlfriend with my new one.  Eventually this fantasy became to overwhelming for me to keep inside and I finally gathered the courage to tell my wife but that is for another post.