My partner and I started off in a monogamous by default relationship. I was really young, only 18, and they were 19. Winter 2014 into last year 2015 I was realizing that I really wanted the freedom and ability to see other people. We had been together 6 years, and I still really loved my partner, but also felt like I hadn't experienced a lot since we got together so soon.
Bringing it up with my partner was so scary. I wasn't sure how they'd react, if we'd break up, what would happen. We also lived together at the time. I cried a lot. They said they needed to think about it. We talked on and off about it for a few months. We never wanted to break up or anything, but we wanted to move out of the house we were living in and were too poor to move into somewhere with just us, so I ended up moving out of that house and into a much better house with some other roommates. Finally, in the summer months, we decided we would be non-monogamous. I went on a trip out of the country for a month by myself, and thought it would be a perfect time to try out Tinder. It totally was! I went on a few dates, but didn't have any sort of physical relationship until I returned back home, and then started meeting a few new people from online like Tinder and OKC.
Things were going great with my partner and my new sweeties, we were communicating well, all on the same page, my partner even met some of my new sweeties and got along well with them. Then I met a different girl, and realized that I didn't just want to casually see her, that I wanted to be able to introduce her to my friends/family and call her my girlfriend. That was another thing my partner & I talked through, and in the end, they realized that my GF wasn't a threat to my love for them.
So now I have a lovely network of sweeties plus my girlfriend and my partner. I feel so lucky to have all these wonderful people in my life. Another added benefit from realizing my desire for poly relationships is that it made my partner realize they were trans and that they want to take steps to affirm their true gender! They are coming out little by little to friends and family and hopefully starting HRT soon! They said they might have never felt comfortable coming out if it weren't for meeting my girlfriend, who from the beginning has been so affirming and welcoming of my partner. She's also trans. <333
At first, it was kind of rocky because they said they didn't really get why I wanted to be poly or why I wanted to see other people, but they recently said the most lovely thing to me -- that after meeting my wonderful sweeties and my girlfriend, they understand poly because the people I have in my life are so loving and wonderful<3