Ex-partner of a person with BPD here.

I've been thinking about the 2.5 year relationship I had with this person. Going back in my mind I think the hardest thing for me in the relationship was the splitting. Can anyone explain why this happens?

Holidays were the worst because we'd be spending days and days together. We'd be having a nice meal and I'd be gazing lovingly in his eyes then suddenly his face would turn sour and he'd tell me that he was furious about my comment about Tom Cruise. Or the way I fold my napkin. Or that I prefer radio to TV. It would usually intensify to a full row with me crying and begging for it to stop. 

It was quite painful to suddenly go from being adored to being quite genuinely hated.

So I wanted to know, when you're splitting have you any idea it's happening? What do you think is going on in your head? 

The things that he devalued me over were often perceived acts of abandonment but they were sometimes random. Sometimes he attacked my autistic traits (intense interests, lack of spacial awareness) which hurt. My self-esteem was damaged by it as it was my first relationship, but now Im keen to find out why this happened and have greater empathy.

Disclaimer: I have always been and still am sympathetic to people with this condition. I am only here to learn, not to judge or belittle.