In 2007, a couple months before my 21st birthday, I confessed to my boyfriend of over three years (who I had been blissfully monogamous with the entire time) that I was having a hard time turning down the advances of an attractive guy at school. The guy wasn't being pushy or harassing, but he was making himself unquestionably available, and I wanted to give in. I had been reading articles about cheating online at night, and stumbled across the suggestion that I talk with my partner about it, so I did.
We agreed that I could sleep with the guy, once, and that I would share all the details with my boyfriend, and decide from there whether we wanted to open our relationship up to strictly sexual encounters with other people. I did, and we decided we were okay with opening up.
I didn't expect to fall in love with another person. It was a hard time reassuring my first guy that I wasn't going to leave him and didn't feel anything less for him. Being the internet junkie that I am, it didn't take long for the word "polyamory" to start popping up in my article readings. Once I discovered it, though, it helped me and my guys out so much, and I'm so glad the communities (and the word "polyamory") exist for jsut that reason.
The relationship with the first guy unfortunately ended as we discovered that we wanted different things in life. I'm still "with" the second guy and have a handful of lover-friends in different places. Most of them are curious about this "polyamory" thing, but for the most part don't see the need to call what we have anything more than a close friendship that sometimes includes sex.