Did she cheat?

I was recently asked if she cheated on me. Borderlines are known to cheat on their partners quite often.

She probably did cheat on me. There were weekends when we were first dating when she would suddenly be unavailable and not speaking with me, so she probably did, early in the relationship. I remember, early in the relationship, she was feeling insecure and paranoid about me cheating, and she said, "you know, if you cheat, I can cheat too."

I was usually quite confident and jovial in my approach to the Borderline. This one struck me hard, and I suddenly got serious, stared right at her, and queried, "what did you say?"

She repeated herself.

I looked her straight in the eyes, and said, "if you cheat on me, this relationship is over."

She never said or hinted that she would cheat based on her perceptions again. Although she still had her paranoid suspicions, she knew better than to say such things to me.

This is the textbook definition of setting a solid boundary for the BPD. The borderline knew that cheating would not be tolerated, so while she continued to think that I was cheating, she would not cross that boundary, or even test this boundary.

She probably did cheat, early in the relationship, before I set the boundary for her. After the boundary was set, she never would have done such a thing.

In the end, it doesn't matter -- if the relationship is so dysfunctional, you should get out. If she cheats, don't tolerate such poor treatment.