I (21NB) have been dating my girlfriend for a little over a year now. I’ve been away in Germany for study abroad, and she’s been back in our college town. I miss her terribly, and our relationship has always been polyamorous but neither of us have really been seeing other people. I always thought I wouldn’t get jealous, that she’d still love me, etc. but lately I’ve been insecure because I don’t have a penis, and I feel like she’d like me better if I did.

Cut to about two weeks ago, when she tells me she’s been having sex with a new guy. At first, this hurt a little, because I felt like it wouldn’t have happened if I wasn’t in a foreign country. But I eventually got used to it and she reassured me that she still loved me the most and missed me terribly.

Then, she tells me offhandedly today that she got a second partner. This hurt me unexpectedly hard. It was different when she was just having sex, but to have an entirely new partner is really taking a toll on me. A lot of it is my own insecurities, but I really don’t know if I can continue this relationship with it still being poly. I’ve begun to realize I don’t want other people, just her. How do I convey this to her without her feeling trapped?