Tl;dr: partner and I had a FWB, right as we started developing some feelings all 3 of us, the two of them had a fight and FWB almost left. I insisted on keeping my relationship with FWB but with a clear boundary that my partner is a priority. FWB turned out to get attached a little which scared my partner and in turn me because I didn't know what to do if my partner wasn't okay with it anymore. I tried to level down the relationship a bit but FWB can't accept that and wants to leave. I realized I feel love also and don't want to lose him. Now I'm asking my partner if he can deal with me loving someone else and he said he'll think about it. Our relationship is strong but it still scares him. I'm stuck between feeling like an asshole for insisting, and yet not wanting to give up the love I feel for my FWB...

Long version: I've had my partner for 5 years. We sometimes talked about polyamory and both agreed we were open to the idea in the future. We even met as he was our third in my previous relationship.

Now for about the last 1.5 years we... met a third guy we connected with easily. We saw him a lot, did a lot of things together and he became a FWB. Sexually things very slowly evolved. We were all taking the pulse relatively frequently and all agreed this wasn't a trio, more like double friends with benefits.

This summer my partner started opening his heart more. There was a particular event involving mdma and he said the word love. As in "I love you two". Not exactly a declaration. But I felt... an opening in my heart too, cautiously.

Then a few weeks later they had a fight. Not exactly something huge, but my partner had insecurities flare up(mdma comedown not helping) and couldn't manage to discuss them with an open heart. For the next month we didn't see our FWB a lot, having to deal with mood issues and exhaustion from work. After all this our FWB eventually got sick of feeling abandoned and said he was out.

I felt horrible and didn't want to lose him. I insisted with both him and my partner that I wanted him around still. Not as a full blown partner, but still FWB. And it being clear that my partner was my priority. So began an assymetrical relationship. They were in an okay but a bit uncomfortable, platonic relationship. Since then there have been some small arguments here and there but things were mostly getting okay.

Then my FWB got insecurities about me being unavailable when my partner has a depressive crash and I sometimes forget to answer texts. In the scope of him building back trust with my partner, he told him about that while I was asleep, wanting to talk to me later about it. But the intensity scared my partner and he ended up talking to me about it before my FWB could. My partner felt this was too intense and the relationship should go back to friendship as agreed a while ago, before this summer's event.

Amid the panick of everything, and being stuck at work trying to make sense of it all, I agreed with that. How could I force him anyway? Talking with my FWB he mentioned he actually loved me which scared me, even if he didn't expectlove back. I ended up pushing for a scale down but not end of our relationship, feeling torn by the feelings of both. But this is not enough for my FWB, and he decided this needed to end. Completely.

After a week of feeling emotionally torn completely, I've come to realize I did get attached more than I want to admit. I didn't want to admit it because I was afraid of what to do if my partner can't deal with it.

But I also can't just shit on my feelings, and my link with my FWB. I don't want to let it die without fighting for it because of my partner's insecurities.

So I asked him. If he could deal with me loving someone else. Our relationship is very secure to me, but of course it is an entire new dimension for him to deal with. He at least understood my position and said he'd think about it.

But I feel like it's torturing him. And I'm being tortured by the wait, not knowing if maybe I'll lose my FWB, and feeling like I'm forcing my partner to accept the biggest thing I could ever ask him, I feel like shit already just asking him.

I am 100% honest, if our positions were reversed I would also feel insecure, but I wouldn't let that affect my decision. As long as he shows me I can trust him and I do love him I would not want to stop him experiencing something else. And I feel like a yes would mean my heart could be free to experience life, which makes me want to enjoy life with my partner even more. While losing my FWB will hurt and make me wilt a little.

I don't feel like I'm asking something wrong. But I don't want to push something on him he doesn't want. I also don't want to lose my FWB. I feel lost and stuck and in constant emotional pain.

If anyone has advice or can offer an impartial opinion, I'd appreciate it enormously...