Hi Gira and welcome.
I am sorry for what brings you here. It is devastating when a partner cheats. This behavior is not uncommon and you will find many of our members are in a similar position.
Your question is a good one, but hard to answer for sure. Impulsive behavior is one of the criteria of BPD and his cheating may fit into that category, certainly if he is also experiencing emotional dysregulation.
Do you feel that if his cheating is caused by his BPD it would make it easier to understand and work on repairing your relationship? Are there other factors that come into play for you?
Hope to hear more from you soon.
