I can sometimes do and say things to sabotage relationships as well without realising. I have a habit of attaching myself too quickly then regretting it not long after as well.
BPD is a tough one to live with. There are a lot of characteristics that I have because of it without even realising.
Because of this, I unfortunately don't have any helpful advice, but I wanted you to know you're not alone
Can you talk to them and explain your insecurities and being scared of getting hurt? Sometimes, honesty is the best policy x