My BF and I have been in a poly relationship and idk if I can take it anymore. What do I do or say?

idk how formatting works. Just bear with me. I’ll tell the whole story (TL;DR at the end).

My (M17) and my BF (M17) have been together for nearly ten months now. We got together very quickly, and didn’t have the typical ‘dating’ period before our relationship started. We’ve had some ups and downs, but our lows never lasted longer than a couple of days, and our highs have always been incredible.

We’ve both had relationships before, but this is our first serious one. Especially for me, this is a big deal. I’ve never felt emotionally safe around somebody before, which is thanks to months of building trust and years of therapy. This, amongst other typical relationship ‘firsts’ have made me extremely attached, and as far as I know he feels the same.

Three months into our relationship, he asks if I would be open to polyamory. I said yes, as I’ve had relationships like that before and experienced them as something positive. At the beginning, this mostly meant him occasionally making out with people at parties, including some of my friends. (Nothing I minded or mind, I’m personally never there, partially because I was at a clinic then, and I’m also just not big on parties).

Four months into our relationship, I’ve been growing closer to one of BF’s best friends (NB18, ‘Friend’). Friend and I really hit it off, they’re an extremely good with handling emotions, specifically my emotions, and I felt safe sharing intimate thoughts and feelings with them. Though I’ve never *showed* those emotions around them. I can’t cry around other people, not at this point in the story. Friend and I wanted to date. I have completely fallen in love with them. The sort of earth-shattering all consuming love that seems to outweigh everything else.

BF did not have an easy time with this. He has anxiety, trust issues and abandonment issues. The thought alone produced fears of Friend and me leaving BF behind together, etc. It was a long, messy period. A lot of assuring, talking, figuring things out. It did work out, for a while, once BF found out my attraction to Friend was more emotional than physical.

I so deeply regret everything I’ve done with Friend. They never did anything wrong, mind you. There was a complicated situation, involving a third party, where they slipped up on an agreement we had, and this third party hurt me (something Friend was there to specifically prevent). I cannot think of Friend fondly anymore at all. It ended ugly, and it did cause a lot of friction between BF and me.

Six months into the relationship, BF has been the only guy for me, and I love it. He still occasionally kisses other people, I don’t mind much.

Enter C (F17/18). C is a coworker of a mutual friend of BF and me. She showed up to a party ones with a lot of other mutual friends, and everyone talked very fondly of her. I wasn’t there (still don’t like parties). People like her. Really like her. So does BF. My brain immediately made an enemy of her. I’m insecure, and having never met this new person everyone seems to adore, she turned into a perfect version of me, who would replace me in every aspect she could. (This thought, of course, is ridiculous).

Eight months into the relationship, a short while ago, BF comes to my house late after work. He tells me he hung out with C, that he kissed her, that they may want to try dating. I was so tired, I said I’d think about it in the morning.

The next while I’ve carefully been avoiding thinking about it. Last week on vacation, though, when I couldn’t see BF for that whole week, the feeling of not wanting to share him with someone else has gotten stronger and stronger. I don’t want him to see C. Not sexually, not romantically, not at all.

Yesterday, I came back from vacation. I told him how I feel. I cried more than I ever have with someone, I think. I told him how badly I needed him, how I couldn’t stand the thought of sharing him, losing him, being second to someone else. How I don’t want to be poly anymore, because I want it to be just us. How I need it to be just us.

It hit him hard. He likes C more than he thought. He got emotional at the prospect of not seeing her (or other people in general), and that hurt me a great deal. I don’t want to feel like I’m taking something away from him. BF has an easier time being vulnerable with potential romantic interests, he can’t tell the difference between platonic and romantic very well, and that makes him hold back a lot when hanging out with friends and such.

He said it especially hurt, because he gave Friend and me a chance that I’m not willing to give him as well.

The next day, today, I decided that maybe it *can* happen. We discussed every possibility. I would need a deadline on the relationship, that’s a hard no from him. A finite number of dates wouldn’t work either. He offered to not preform certain acts of physical intimacy, but that doesn’t ease my worries. I don’t care that he generally does stuff with other people, I care how often and how much he focuses on a single other person that isn’t me.

I was supposed to meet C today for the first time. I couldn’t. I’ve been crying all day, and BF said maybe it’s better if I just have some rest. He’s off to see her right now, updating her on the situation. Because of my troubles with it, we’re waiting longer. I’ll meet her another time. We’ll discuss further another time.

Now I’m sitting in my kitchen, writing this right after he left. I can’t stop thinking about him with her. I can’t have it. I don’t want it. I can’t share him. It hurts too much to share him. It makes me feel like I’m not enough, like I’m replaceable, like what I have with him isn’t special. He’s said things to try to ease these feelings I have, but I can barely hear it. It just doesn’t seem to help.

I don’t know what to do. I do think he ‘deserves’ the chance he gave me as well. He put his insecurities to the side, which ended up making them weaker in the long run, and let me do my thing with someone else. But I just can’t. I can’t do it, I don’t know how. And I feel like a horrible boyfriend for that. I feel so guilty. If I were to tell him to never see C again, he’d do it. But, God, he’d be sad. I don’t want to do that to him. I don’t know what to do.

I’m looking for advice, I guess. Or just someone to tell me what they think. I feel like I can’t think of all this objectively. Thank you for reading.

TL;DR : BF and me had an open relationship, he’s been physical with other people, and I’ve had an emotional connection with one other person. This was difficult for him, but he allowed it anyways. That ship sunk hard. Now that he wants to be emotionally involved with someone else, I don’t think I can deal with it. I don’t know what to say or do.