I am very new to my BPD, having for years just thought I was suffering from depression. One thing I notice more now is the alternating of my emotions toward a person during any one given day. 

I'm currently seeing someone, and my emotions towards her can go from intense giddiness and love-like feelings to intense hatred, within seconds. She was here a few days ago at my place, and she was looking in the mirror - I also needed to use the mirror and I was becoming increasingly angry and full of rage that she was taking so long. 

I had to leave the room and I stood in my bedroom, tense and annoyed. Within five minutes, I was fine and we were cuddling. 

I asked her this morning whether she wanted to meet up and she said she doesn't know, so that caused me to be close to tears and convinced she doesn't like me anymore. I've calmed down now (although still a bit upset) but the way these emotions and feelings alternate like this is truly exhausting. 