I have spent the last four months separated from my girlfriend by 2000 miles, and I have seen her only four times in that period. Our relationship is nearing 2 years. This past weekend I was at a going-away-party hosted by my colleagues, and it was very pleasant. There was a lot of wine, good conversation and a relaxed atmosphere. One of the girls - in a relationship, very attractive, and the same age as myself (25yrs) - has a previous reputation for being somewhat loose. And I was also attracted to her a few years ago. Although I have had respect for her both professionally and personally, I have been very critical of that particular aspect of her behavior. As it happens I got as drunk as I had planned, but I had not planned on falling asleep on the couch embracing this girl, as if it was my girlfriend. To me this is a clear violation of the terms of my own relationship. When I woke up the following morning, I called my girlfriend and explained to her what had happened. However, I have not been able to explain to neither myself nor to my girlfriend why I allowed it to happen. Did I like it? Did I forget my obligation to remain faithful? Have I secretly been wanting this to happen? Did I seek confirmation? Either option is extremely difficult for me to accept, and I have always hated people who aren't true to each other. I feel that I was right to tell my girlfriend about the situation right away, despite the pain we are now both feeling. I do feel as if I have cheated on her, and I don't understand why I did it. With all my principles and experience with alcohol, I had never pictured me in a situation like this. I am hoping to mend our relationship, but I feel that I must first understand the reasons that led up to this.
Any opinions and input is much appreciated. Am I missing some biochemical factors? Am I lying to myself? Am I trying to save face?