I know this isn't exactly one of the diagnostic criteria for BPD, and some may categorize this as an overreaction of sorts, but does anyone have a tendency to obsess over things?

My family tells me that I have a tendency to obsess over things a lot. If it's a rejection or breakup, I can't let it go, and I have to fix it. For example, even if it's someone that I'm not "dating", and this could be someone that I haven't even known for very long, I can't accept it if they reject me or don't give me a shot. I take it so personally, and keep trying to figure out what I did wrong that makes me not worth their time or affection. Plus the, "let's be friends," thing always comes up, which I try, but it becomes a toxic situation; I can't stop thinking of them as something more, and I keep trying to make it into something that it isn't, because I think that there MUST be something I can do to change their mind, but then it turns into an unhealthy situation and I usually wind up burning a bridge.

If it's an interest or hobby, I need to learn EVERYTHING as soon as possible, research everything, find out everything there is to know, spend what can sometimes be an absurd amount of money on said interest, and then forget about it in a week or two.

It happens even with the stupidest things... I could have something incredibly important to do, but I can't do it if there is something else on my mind, because that other thing completely consumes my thoughts.

Once my mind takes interest in something, I fixate, and then I fall down the proverbial rabbit hole.

Let me know what you think. Is this normal, or at least somewhat common?