I actually have a hard time reminding myself of that. I always feel like I'm guilty, and the root cause of problems. My ex was very standoffish and refused to learn about my BPD. To him I was a 'special snowflake'.
But thinking back, I was the doting affectionate one in the relationship. Most of my splitting and outbursts were caused by him making me feel crazy, or refusing to treat me with more compassion. But because I couldn't think clearly, I told myself that it was my fault and I was just overreacting.
Perhaps I was overemotional, but I know if I didn't have BPD I would've realized that it was my subconscious telling me to leave him because he was toxic.