I have a similar issue, and what it sounds like bpd (borderline personality disorder) for me it causes me to obsess over every moment we're not talking and what I mightve done wrong even of I did nothing. For me it makes it hard to let go of things people do or say or eve just friendships that have run their course.

I do this all the time. When I was little I would obsess over one friend and not want them to hang out with anyone else. Now as an adult it's more potential partners I obsess over. If they don't text me back immediately I think I've are ignoring me and I phone watch. Or I'm terrified of saying or doing something that will chase them away. I'm afraid they will think I'm crazy or weird because of my mental struggles. I try to hide my obsessions but it literally consumes me. All I think about it them and how I want to talk to them and see them and how I don't want them to talk to any other girls cause I get insanely jealous. I hate it and I want it to stop but I don't know how to stop obsessing

I'm the same exact way. Never figured out how to prevent it.