Most Helpful Guy
Maybe, when you were talking, his relationship with the other girl had not quite arrived at the corner of Exclusive Street and Monogamous Boulevard, so he was still playing the field. If he has since settled in with Miss Right, maybe he doesn't know how to explain it to you gracefully.
Maybe he was already exclusive with his girlfriend and he was tempted - started to drift - but then realized what he was doing, slapped himself in the face and told himself he as a bad boy. If so, he would be embarrassed and not know how to explain that to you.
Most Helpful Girl
Ahaha i connect with this on wayy too many levels, i recently had the same problem except im meant to be going to a party that he invited me too next weekend but from my experience they do it because they are initially interested and then they become cautious about getting caught out