How I missed my chance to have a threesome

Back when I was 21 years old (so many years ago) I was dating a girl who was 18 and still in highschool.

Everything was going fine with the relationship - so I thought - until I found out that she was seeing 7 other guys on a regular basis.

And I was like WTF? Why are you seeing (and sleeping with) 7 other guys?

And she responded that she is just friends with them - friends with benefits. And that I was the same thing, just a friend with benefits.

Myself I was quite heartbroken. So I gave her an ultimatum, break it off the other guys and go out with only me.

Because quite frankly I wanted a monogamous relationship. I didn't want to share her with other men.

She said she would think about it.

Then out of the blue her best friend, a girl she hangs out with a lot whom I had previously met, calls me up and wants to hang out. Clueless, I say okay. So she comes to my university and we hang out on the campus and in my dorm room and I get the distinct impression she is hitting on me. She was saying things like how her boyfriend wasn't doing it for her any more and she was thinking of breaking up with him, etc. Basically trying to put the moves on me.

Meanwhile I am still in my monogamy frame of mind and I politely just hang out with her, nothing happens and she eventually went home looking disappointed.

Now at the time I thought my girlfriend (if you can call her that when she is sleeping with 7 other men) was just sending her friend to spy on me. It was pretty obvious that this was a setup for something - I thought it was to see if I would cheat on her and so I did not.

However I had interpreted everything all wrong. Years later I have finally figured it out.

Her friend was there to determine if I would sleep with her, and then the two of the girls together would somehow (deviously) organize a threesome or some kind of group sex event.

It is blatantly obvious now what their plan was, but at the time I was young, naive and clueless.

I am certain it would have ended badly too. I am too much of a monogamy person that I would have gotten jealous of her sleeping with other men. Other women I could deal with, but not other men.