I think that’s when things started to get complicated. I realize now that, while we weren’t exclusive, we also hadn’t clearly communicated our expectations. On the one hand, I didn’t expect this to last forever; I braced for the day when Kara would come to us and say, “I met someone special,” and I promised myself I would have the grace to let her move on to the next phase. But on the other hand, we’d said the "L" word. We were incredibly close. A sense of ownership had started to creep into my mind.

The group dynamics were off, too. When I went home early one night from a party, and Ryan and Kara didn’t get home until eight in the morning, I fled the apartment and refused to take their calls because I felt left out. But Ryan was usually the one who felt left out, when Kara and I would gang up on him about a feminist issue — or when she and I would have sex, just the two of us.

The balance in our relationship was swinging back and forth wildly. When Ryan and I brought Kara to a second sex party, she locked herself into a bathroom with a guy for three hours — a guy we still maintain is a douchebag and not good enough for her. I couldn’t bring myself to speak to Kara all the way home. Ryan wondered what this guy had that he didn’t. We talked it out for hours that night, but something had changed.

We didn’t hang out with Kara for a few weeks after that. She was busy working two jobs, and Ryan said he needed some time away from her. Then, one night, I booty-texted her at 3 a.m., and she said she couldn’t come. She was at a sex party without us — and was going home with the douchebag.

Imagining Kara traipsing around the sex party, where we had first brought her, in her lacy lingerie, fucking strangers, kept me up all night. I felt ugly and hot inside — a new sensation for a girl who prides herself on being "above" all that jealousy bullshit.

How was it possible that I was falling to pieces for this woman when I had never batted an eye at Ryan going out on dates with other girls? I think it was because Ryan has always overwhelmed me with his love and consideration. I could bring him back to my side immediately with nothing more than a text saying I was feeling lonely. He always checks with me before making any moves with other women.

But Kara was under no obligation to us. She hadn’t even thought to ask us how it would make us feel if she went to the sex party without us. But should she have? Ryan and I were the couple, and Kara was always just orbiting around us. She didn’t get the full emotional support — or the responsibilities — of being in a relationship with one person.

Ryan spent that week comforting me and talking me through my first heartbreak, as I came to terms with the fact that our relationship with Kara was no longer working. Ryan had moved on a while ago, when he realized that even though Kara loved and respected him as a friend, she seemed to be tolerating his penis in order to be in bed with me.

The next time Kara came over, we broke it off. “I loved you,” I told her during our eight hours of conversation and crying. “I’m grateful for our 10 months together. But I can’t do this. I’ve boxed up my feelings and put them away.” She didn’t fight our decision. She too felt hurt by my viewing her as an object we could own.

I haven’t seen Kara since, but I’ve texted her to tell her that I’m thinking of her. I don’t want her to feel like Ryan and I dumped her and then moved on. She was, and is, important to us.

Some may see this as a cautionary tale against triads. But it’s not that at all. Even though it didn’t last forever, all three of us got a lot out of that relationship: friendship, excitement, and yes, pleasure. I could never regret the 10 months of magic that Ryan and I spent in the company of a unicorn — but it’s also true that that magic can’t protect your heart from the hurt of saying goodbye to someone you love.