[delay]

I wondered after that incident how her behavior and her approach to being naked in the apartment might change. This was a girl, after all, who really liked being naked, always slept naked even when she was alone. But, fortunately or unfortunately, she kept her clothes on around my roommate for the most part during the couple of months that she stayed there. But it did create a certain kind of bond and erotic edginess with a third person that I enjoyed...
There were two more incidents, one brief and one more extended.
The brief one: it was late at night, we had got home from a party, we were both a little drunk but not sloshed. She went into the bedroom, and I went into the living room with my roommate. I felt like having another drink and listening to some music. I guess she was ready for me to join her in the room, though, because a couple of minutes later she walked into the living room and said to me, "I'm going to bed". She was completely naked. I motioned for her to come over, and she did. She took a sip of my beer and then went back into the room. My roommate was speechless. I went and joined in the room very soon after!
The longer time was one morning on a weekend. We were supposed to go and visit my parents, and she was in the bathroom getting ready. I was showing my roomate something on the computer in my room. My girlfriend came into the room with her towel around her. We glanced at her, but we were both focused on the computer. I figured she would get what she needed and go back to the bathroom, or dress discretely. We were looking at the screen for a while, I think, when my girlfriend began saying something. My roommate and I turned around to look at her, and she had gotten rid of the towel and was calmly and methodically putting lotion on her body. My roommate didn't go anywhere - he was sitting in the chair - and the three of us carried on some kind of casual conversation while she gave us a demonstration of how to thoroughly cream yourself. This took at least four or five minutes. When she was done, she didn't get dressed but walked over to the computer to see what we were looking at and leaned over so that her nipples, which were always a little hard, were about six inches from my roommates face.
I was super turned on the whole time, this combination of beauty, confidence on her part, jealousy, insecurity and admiration on mine, was almost too much to bear. I felt like she wanted to please me, but I also felt like she was showing me up, diminishing my special place as THE one who "gets" to see her body, and maybe she was showing my roommate what he could be getting. I felt stupid for allowing this to happen, but I also felt grateful that she was turning me on in a way that no one else ever had. And it would have been hard for me to put a stop to it without revealing my own insecurity, which I didn't want to do.
So I played it cool, and she hung out for a couple more minutes before she went to the bathroom and brushed her teeth, still naked and with the door wide open. When she came back to the room, my roommate was in the kitchen. I watched her while she was deciding what to wear, taking her own sweet time, and I was in a bit of a bind. I didn't want to go in the shower while she was still undressed - who knows what could happen? - and I didn't want her to get dressed either. But eventually she did...and then moved to a new place not too long afterwards.