As a preface, I’ve been monogamous my whole life and I’m new to poly. My new relationship just became serious in June. My now girlfriend expressed to me a year ago that her and her boyfriend wanted to open up to poly, and that I was one of the first people she wanted to contact about it. It's taken me almost a full year of therapy in order to feel like I'd be a good partner (l've been in multiple monogamous relationships and I was almost always the reason they failed, and I want to be better this time). I've been putting a lot of work into improving myself and I finally felt ready to make it official in June. We've been having the "serious relationship talks" since then and I think it's finally clicked for me that maybe I'm not ready for this relationship. She is in a throuple with her original boyfriend of about 5 years and with another woman, who they've been dating since they opened up to poly a year ago. They've had a full year to get used to the dynamic and they want to have kids together. I do not want kids. I also don't want to be secondary (I read a few posts from r/polyamory and I think I understand what that means?) — want to be a primary just like her other two partners. I finally realized this today. I'm heartbroken because I'm thinking of the pain I would experience seeing her have kids with her primary partners while I'm off to the side. I don't feel that she loves me any less, but I do feel like less of a priority because I don't want kids. Anyway, I don't want to break up with her because l've put so much time and work into improving myself and I've finally accepted that I'm in love with her. And I would never ask her to change, yet I don't think I can change how I feel either. What do you all recommend?