CW: Jealousy, possessiveness, worthlessness

Hey lovely people, I hope you can help me find some perspective on this because I'm feeling incredibly lost. Please bear with me if my post seems long and incoherent; I'm having trouble organizing the thoughts in my head.

I'm in a relationship and having trouble setting healthy boundaries without enabling my toxic traits (mainly intense jealousy due to feelings of worthlessness and low self-esteem). I am currently in therapy but making very slow progress in this area.

I've faced this issue in previous relationships but not to this extent; perhaps because this time I'm dating someone who is very extroverted. He has a lot of female friends and they are generally very emotionally (and sometimes physically) affectionate with him.

He seems willing to accept/discuss my boundaries if I verbalize them, but I don't know what my boundaries are. It seems like most of the things I am not okay with are generally acceptable among most of the people in my circle, so I feel like I'm being unreasonable and controlling. At the same time, I am terrified that I'm setting myself up to get hurt just to seem like an accepting and progressive partner.

My question is, where is the line between reasonable and unreasonable? Any insight or perspectives would be helpful, because I'm starting to think that maybe I just can't function in a healthy relationship anymore.

I'd add some examples but I'm worried the post will be too long and no one will bother reading it. If you've made it this far, thank you for reading.