I thought I was good at managing, how can I be sure of that?

Hello. Sorry for the throwaway account, my fp knows my reddit handle... This is some kind of a vent, I'm sorry.

Me and my fp (autistic and avoidant) are going through a rough patch. This is a horrible experience, worst than any other breakup I can remember because I keep swinging between the need to breakup and flee and stay to make things work. There have been underlying communicating issues that we've kind of been avoiding and they have undermined our relationship so much that we had to sit down and talk about it.

I never told them about my BPD, as I've only been diagnosed a couple months ago and it's though to fight the fear that other people may see me as unstable. So I don't say stuff like "I'm triggered by... / I have moodswings because...", I just say that I need a more clear communication. We had a thorough talk, and I was so proud of myself, I was glad I could address it and I could also be present for my partners emotions (I guess 15 years of therapy, even if not diagnosed, we're a huge help for my empathy). I asked them about their opinion, I gave them space when needed, we took a break when the talk became overwhelming for them, I thought I was doing everything in the right way.

I told my therapist and they really said they were proud of me for this big accomplishment, since I've always let myself simmer in the fear of abandonment without trying to open up about it.

It's been two weeks, and even though my fp agreed that they could be more comunicative with me and try to give me a bit of reassurance when they were distancing, they still aren't. They put up a wall and only let me in seldom.

What did I do wrong? I thought I was an overall okay partner, I thought I was empathetic. They always told me how much safer they felt, and yet there is still a wall that won't come down. Maybe I could be more understanding. Maybe I was THINKING of being supportive and in reality I wasn't.

Is there some book I can read, or some cheatsheet that I can look at, with boxes to check, so I can understand what it takes to be supportive and empathetic?