This question takes me back to the most painful moment in my dating life. My answer to the question would have closely matched everyone who answered above, but...
There was mutual love between a woman and I. We were not in a relationship (I wouldn't do it), but she asked me to be monogamous and, because I loved her and wasn't thinking about other women, I agreed. After about a year, she became distant. I knew there was someone else, of course, but what I didn't expect the feeling that overwhelmed me when I received an email that stated, "guess what I did?"
A woman! It took me two seconds to figure it out. She had a relatively new female friend who she never mentioned to me, so I think the intent was always there. I cannot put into words the amount of pain I felt over this. It had nothing to do with it being a woman, it's the betrayal of a loved one that's truly painful.
