Well...no, not really, actually. It doesn't really affect my ability to trust...cuz, well, I never trust implicitly. 
Trust must be earned. Actions mean much more to me than words. Were I with a girl, and through some means or another, I found out some guy she had had a crush on for a very long time proposed to have sex with her discreetly, and she turned him down, that would pretty much be as much proof as I could possibly expect to get that she intended to remain solely for me. And if she DID partake, so to speak, but confessed it, I would forgive her, and still trust her because despite her actions of "betrayal," she would be showing regret for it, and the emotional attachment was clearly strong enough to elicit such guilt that she felt the need to tell me which clearly means she truly cares for me. I'm not so vain as to be that guy whose woman sleeps with another man and they can't stop thinking "THIS IS WHAT SOME OTHER GUY SAW! AND SHE TOOK IT WHILE WE WERE TOGETHER!" because clearly whatever she felt for me stacked up much higher than whatever pleasure the experience brought.
I might even take it as a compliment; if she admitted to it, chances are that while there might have been some thrill in experiencing something new, clearly the talents she is more used to were far superior and she desperately wants to see if honesty will ensure she keeps it.
Personally, I DID 'cheat' on a girlfriend once but for certain reasons. She was becoming very domineering and controlling and was not respecting my desires in any context. Everything was about her, her, her. She felt herself superior to me and that being with me was a favor to me from her. I disagreed. I had sex with another girl. The other girl was far better in every respect. I dumped the stuck-up bitch, dated the other girl, stayed with her for a solid year, then parted on good terms with her when we finally realized that the spark hadn't kindled an outright flame but had still provided plenty of warmth in the time it existed.
Trust and romance are funny things.
Trust must be earned. Actions mean much more to me than words. Were I with a girl, and through some means or another, I found out some guy she had had a crush on for a very long time proposed to have sex with her discreetly, and she turned him down, that would pretty much be as much proof as I could possibly expect to get that she intended to remain solely for me. And if she DID partake, so to speak, but confessed it, I would forgive her, and still trust her because despite her actions of "betrayal," she would be showing regret for it, and the emotional attachment was clearly strong enough to elicit such guilt that she felt the need to tell me which clearly means she truly cares for me. I'm not so vain as to be that guy whose woman sleeps with another man and they can't stop thinking "THIS IS WHAT SOME OTHER GUY SAW! AND SHE TOOK IT WHILE WE WERE TOGETHER!" because clearly whatever she felt for me stacked up much higher than whatever pleasure the experience brought.I might even take it as a compliment; if she admitted to it, chances are that while there might have been some thrill in experiencing something new, clearly the talents she is more used to were far superior and she desperately wants to see if honesty will ensure she keeps it.
Personally, I DID 'cheat' on a girlfriend once but for certain reasons. She was becoming very domineering and controlling and was not respecting my desires in any context. Everything was about her, her, her. She felt herself superior to me and that being with me was a favor to me from her. I disagreed. I had sex with another girl. The other girl was far better in every respect. I dumped the stuck-up bitch, dated the other girl, stayed with her for a solid year, then parted on good terms with her when we finally realized that the spark hadn't kindled an outright flame but had still provided plenty of warmth in the time it existed.
Trust and romance are funny things.
