Ughhh please

I am so frustrated and upset. We just finished a major split two weeks ago. We didn’t speak for an entire week and it was honestly a big mess. Then the next week, I’m back to being his favourite person. I saw him almost every day and it was wonderful. No fighting, just happiness and fun.
Everything was fine until just now. I called him and he let me know he was going camping by himself in the morning. I said okay, no problem. Be safe and have fun!
He was asking about my car (it’s been having some trouble), and I talked to him a little about it. Then he said some remark like “sometimes I wonder if you only got the car so that I would stay interested in you”. I was honestly taken aback and told him that was an extremely narcissistic and egotistical thing to say.
I tried to tell him that I definitely didn’t get the car to keep him interested but I am happy that it gave us so much to talk about with each other. Then he started talking about how it seems like even though we talk all the time, we only really discuss the same two or 3 subjects. I mean, admittedly probably 70% of our conversations are about cars but it’s a shared interest. He talks about his car as much as I talk about mine and we both enjoy it...at least, I thought we did? He started saying how he wanted to be with someone he could talk about other things with, like music and anime.
Again, I was completely taken aback. In our 2.5 years together, never ONCE has he mentioned anime or brought it up as if it was important to him. I jokingly made fun of one of his CD’s a few days ago and apparently I really hurt his feelings. He’s still upset about it. He then said he was hurt that I never asked him to play any of his records.
I was so frustrated and angry at this conversation because I’m tired of being guilty for things I had no idea were even issues. But anyway, I did my typical quick reaction and got mad and defensive and of course the conversation went downhill and turned into a fight. Then we just hung up the phone and I expected that to be it while he goes away and isolates himself in the woods for 2 days and I just have to sit here feeling bad and anxious about our argument.
So anyway, as I was typing this all out, I realized that I, once again, forgot everything I knew about BPD. It dawned on me right away that I invalidating his feelings and argued with what he was believing. As an experiment, I decided to take a deep breath, and call him back using the techniques I’ve learned here. I told him I was upset by our conversation but I could understand why he thinks we only talk about the same few subjects. I told him that i was sorry I didn’t realize anime and music were so important to him and if he wanted to share those things with me in the future, I would be more than happy to listen, learn and discuss them.
Then I told him as we both share more experiences about our lives, we would probably always find more things to talk about. Lastly, I said that there were probably lots of things I would want to talk to him about that I just never have, and maybe we could have some more interesting conversations.
He immediately calmed down and backed down. He thanked me for calling him back. He let me know that sometimes when he says stuff like that, in some twisted way, he’s usually just trying to keep me talking to him because he misses me. And i recognize that to be true as this has happened before and he’s said this before... but for the life of me, I can’t understand the thought process behind it. It seems like the worst way to talk to someone you miss. It’s like shoving someone out the door with words and then blaming them for leaving.
Anyway, I SORT OF see his point. I don’t want to be one of those couples that stops talking to each other. It was just shocking to hear because we usually spent an hour or two on the phone every day just talking about EVERYTHING. It was a very strange accusation that I can’t wrap my head around.
BPD is confusing and frustrating. I don’t even know when it’s BPD anymore. And our conversations are always SO nice before it gets turned on it’s head by one remark.