Long story short, I went to a club this past weekend because of my friends birthday party and I told my girlfriend about it and she's fine with me going clubbing. Anyhow, I drank a little too much and when I drink I love to dance to house music. So when house music started playing there was a random girl near me who I signaled if she wanted to dance with me. The dancing involved like 30 seconds of somewhat grinding, where I held her hips and hands, but didn't touch her anywhere else, I did not feel up on her either. I did not get aroused either, I guess I just wanted to dance with someone. After the 30 seconds of dancing we pretty much danced for like a foot apart and I signaled her again if she wanted to dance but she kindly declined and then ended up dancing with my friend. I then ended up dancing by myself. We never defined this before in the relationship and I asked her what her thoughts were about the idea, but I never told her about what actually happened because I think it would hurt the relationship more. However, her ideas about a situation like this arising is that she doesn't view grinding as cheating but thinks its very inappropriate and wouldn't want me dancing with other girls. Should I feel sad or guilty or should I just forget about it? She does not know these group of friends. I DID NOT tell her about the incident I just asked her what she thought about grinding in general because we never defined it in our relationship until after it occurred.