My son has same likely bp & bpd. But he's on the other end. Won't settle down with one girl. After a few days they drive him nuts and he tells them he's not trying to have a gf. Too overwhelming for him. Mass abandonment history & I think he just can't be with anyone on that level yet. My boys 18 today, they will figure it out in their own way, only so much we can do. Therapy is good if he's willing to go talk to someone.
I should add that he does not like it when I or his older sister leave the house for work & I often get yelled at for leaving him alone.

. He was a nice boy today though.