Well, maybe it's just me but I'm thinking of another aspect to the story. This could be a good thing that it happened, maybe it put your relationship with the b/f into question for you. I don't know how young you are but it is better to realize that the relationship is based purely on comfort than on love when your young than to find out that you are just with your b/f because you've been with him so long, especially if the relationship progressed to marriage. I personally think that your just with your b/f because you've been with him so long that you don't know what else is out there. If you're willing to take someone home to have sex with that you've barely talked to then obviously the issues aren't with the attraction to the stranger, the issues are with the relationship itself. Having sex with someone else on the same bed you and your b/f sleep on every night is like having sex on your parents bed,,, ewww!!!! Plus, I think, actually I could promise, that the guy isn't at the gym anymore because he doesn't want to see you again. Things would probably be too uncomfortable for him, and now that he knows that he could get you into bed at the drop of a dime, he probably is on to his next banger; or his actual girlfriend.