I went out last night with my roommate and we met a couple girls at the bar. Drinks ensued and I was the wingman. When we got back to my place he went straight into his room with girl #1 leaving me with girl #2. Seeing as I wasn't about to call a cab for girl #2 and leave her friend (girl #1) at my place with my roommate, I decided to let girl #2 stay over... in my bed.
I've been in a serious relationship with another girl (who is currently doing a four month internship in another city) for over two years now, and I just might marry her down the road. She is not girl #1 nor girl #2. Is it really bad to spend the night with another girl even though I didn't touch her or make any sexual advances towards her? And how should I approach telling my girlfriend about it? I do want to be honest.