That gives me some more information that certainly answers some of my concerns. Thanks for being understanding and mellow about the fact that I had and voiced concerns.
I do think that it's important to talk about if YOU want monogamy or not, and if you feel able to say if you don't. I also think it's important when you're in a relationship with someone with BPD to just be extra cautious about if you're doing anything (or not) because you feel like you're walking on eggshells, or if that person has, in any way, set things up so that they make all of what they want needs so the other person feels they don't have real choices. If you don't mind my asking, are you telling your therapist the same things you're telling us about this relationship? If not, I'd just suggest you do: they're going to be a potentially great resource for you in having a relationship with someone with BPD, which really is it's whole own thing as a thing, if you get me.
But if you actually WANT to try monogamy for yourself, then obviously this is a whole different situation.
I think what might be most helpful to you in this is just to share some super-basic stuff that I've generally done for myself as someone who has lived in and with both frameworks, and who generally prefers sexually open/nonexclusive frameworks and agreements, but has also spent a lot of time in exclusivity, some I did want and felt good about, some when I was honestly over it.
I think it's helpful to remind yourself this is a choice and an option, and you can always change your mind. So, if it turns out you really do want to follow up on this curiosity and date others, you will have the choice to do that. All of this is about choices.Same goes with this choice being about what you want and feels right for you. If monogamy feels like the right things now, but stops feeling that way later, you get to make different choices later and ask for different things. You say you can't explore these things "for a super long time," but that'll only be true if that's the choice you have made and keep making.
You can engage in fantasy as much as you want to, whether that's just in your head, something you bring to masturbation, or, if your partner is into it, something you bring into your sexual partnership as either fantasy or role-play.
I would challenge you on the idea that poly = noncommittal. Poly relationships can be -- and many are -- as committed and daily and long-term and involved as monogamous ones, sometimes even more so. In fact, it's one of the last places I'd suggest someone who doesn't want to make commitments go exploring, tbh. You might also figure you can use some of this time to think about if what you want is poly, or what you want looks more like plain old dating. Sometimes being exclusive for a while does allow you some time and breathing room -- and also the experience of being exclusive -- to get more of an idea of what you do really want.