Hi Zienna,
Mostly my family friends really do not understand & a favourite is "well I couldn't do it I haven't got the patience"
I can understand how invalidating that feels when family and friends wouldn't put up with it, it's easier to observe someone's r/s and critique them then actually being in the r/s, it's more complicated then that. You have feelings for him, you love him.
I know how the push behavior hurts, I lived with my wife, I take it that you don't live together? Anyways, my wife would give me the silent treatment, she was pushing me away, it was really confusing and it hurt, but what also hurt is that she would blame me and say that I was giving her the silent treatment. She was projecting, do you know what projection is? You're bf is projecting when he is saying that he feels sorry for you, that's the reason why that he's back.
If he has BPD it's a life long mental illness and the behaviors are not personal to us, BPD is not something that your bf can control, it's something that he's going through, it helps to depersonalize the behaviors, become indifferent to them, you neither like it or hate it, it's a process, it takes to time to depersonalize the behaviors, but it works.
Also, your bf is who he is, I'd recommend to radically accept him for who he is. Radical acceptance is instead of going against reality, for example hoping that our pwBPD are going to get help or that they are going to change it causes a lot of pain and unnecessary suffering, we accept that they have a life mental illness, my pwBPD has social impairments, sometimes the behaviors hurt me, or it makes me frustrated but it's no under his/her control.
It doesn't mean that you can't feel frustrated, angry, or sad with radical acceptance, it means that we accept things as they are, we're no longer fighting against reality, we embrace it.
Radical Acceptance For Family Members (DBT skill)