Bf wants an open relationship and I’m not sure…

Hello!

My boyfriend wants to be in an open relationship (again). We did this before and he wasn’t exactly respectful of me and he broke a lot of the boundaries we had set. We ended up closing the relationship when he hooked up with someone on his birthday because after he did it he said it didn’t make him feel good and he really just wants to be with me…but now 6 months later he’s brought up wanting to do it again and I’m just so hesitant…

anyone with any experience in this?