My girlfriend, that girl from class, and their friend, or, how I lost my virginity (m/f)

I had my first “real” girlfriend, who I will call Rachel, when I was 17. We’d been seeing each other for a bit, and I’d had a couple really intense make-out sessions with her, including one that wound up with her on top of me in the driver’s seat of my car, dry humping the shit out of me in her parent’s driveway.
One night, we’re out for a drive and she asks if I want to stop by her friend Monica’s (nod) house. I knew Monica from the biology class we took together, and I liked her because she was weird and unashamed, so I had no issues agreeing to saying hi. We were at Monica’s house for about five minutes when Rachel asked Monica what her friend Pete was up to. Apparently Pete had a long-standing crush on Monica, and she had zero interest in Pete. She said he called about hanging out earlier, then admitted she wanted to get out of the house, “even if it means hanging out with Pete.” So I drove the three of us over to Pete’s house.
Pete had exclusive rights to the entire downstairs of a split-level house, complete with a padlock on the door. It was a little strange to be locked in a basement (albeit finished) with and by somebody I’d just meant, but I just wanted to go where Rachel went, so I shuffled in without a word. We sat for a while and shot the shit, and I immediately understood Monica’s reluctance with Pete. He was a little off, kind of short and the embodiment of a napoleon complex. He also had really good taste in music, so I could focus on that and ignore everything else. We were in the middle of a pretty intense game of “Have you heard of…” when I felt a hand on my leg. Rachel was looking at me intensely when I turned to face her, and she leaned over and kissed me. We went directly into passionate, sloppy teenage make-out right away. After a bit, I realized that this was the first time we made out where we weren’t in my car, so I got a little bit more bold, grabbing one, then both boobs. Rachel had zero issue with me playing with her tits, so I tried to take her shirt off, and she threw her arms up to make it easier to get off. I fumbled briefly with her bra before undoing the clasp and freeing her perky b-cups. I buried my face in her chest, licked and nibbled on her nipples and went back to making out. I dry humped the shit out of her for a change, and she reached down and played with my cock, which was already hard as fucking granite. I had her pants open and around her ankles, then off in about two seconds. She wasn’t wearing anything underneath, so I went right for her clit with my fingers, then I figured fuck it, and went down on her. I can’t be sure, but I think I was down there for about five minutes, then she pulled me up and we made out more and she cleaned herself off me.
Then the strangest thing happened. She got off the bed, and I noticed Monica had left the couch where she and Pete were doing their thing and the two girls started making out. I wasn’t sure what to do. Did they want the guys to make out? Did he want to make out with me? Is there some kind of signal, or am I just supposed to know? What the fuck is happening? Then the girls split up and Monica came to me, and Rachel went to Pete. Monica wasn’t much in the face, but man, she had an amazing body. She pushed me back to lay down on the bed and told me she was going to suck my cock, then added, “Is that okay?” I nodded furiously in the affirmative, and she took all of me in her mouth, down to the hilt. She gave an incredible blowjob, and of course, I didn’t last very long. I told her I was going to come, and she said, “Well, come then!” And my hips bucked as I exploded into her mouth. I looked over at the couch briefly and Rachel was giving Pete one hell of a handy. I expected Rachel to stop, but she didn’t. She told me she wanted to get me hard again, because she was going to fuck me. That was all I needed to hear, I guess, because I was hard again almost immediately. She told me she had to be on top, and that she hoped that was okay. Again, I nodded yes as if my life depended on it, and she climbed aboard. She was a treat to watch as she got both of us off riding and writhing and grinding and bouncing. Again, I looked over to the couch and Pete was railing into Rachel, just pounding her. Maybe it should have bothered me, but it didn’t, it was like having live porn to watch as I was having sex. Well, I guess that’s exactly what it was. Before long, I felt the intense, growing pressure and Monica frigged her clit so we came at the same time. After, she just laid down on top of me, and stayed there until our breathing slowed back to normal and I became flaccid and plopped out. It was a strangely touching moment, as the other two were already getting dressed.
I think I smiled ear to ear for the next day and a half. It was annoying, because I couldn’t stop doing it. Rachel and I broke up a couple weeks later without ever actually having sex. Oh well, right?