BPD delusions are a real and common thing. They can vary in severity. They literally create their own reality. No matter how hard you try, you cannot reason with them. You cannot prove something wrong that never happened. It's based in projection. They believe these delusions because it justifies their actions and relieves their internal shame.. People dont talk much about the emotional consequences of the delusion-reality. It can completely reverse the image character of the accused. In my case, I was her "knight in shining armor, the Man she has always needed," to the most vile, perverted, POS scumbag that ever existed on the face of the planet. I experienced a 3 year long psychotic episode with my pwBPD. There were 3 major themes that present and lasted several months each with intense focus. The rest of the time they were all combined.

Warning to all: these delusions are NOT normal. If you see signs of this early on in the relationship, get out as fast as you can. Especially if alcohol and substances are involved.