I'm currently in a long term relationship (13yrs) with someone suffering from BPD. We have a two year old together and I feel as though we've hit a rough patch and I'm not sure if we can recover from it. He's currently in crisis due to a 'favourite person' relationship he's developed, this is a fairly new term we've learnt but applies to alot of past relationships with people over the course of our relationship, we just never linked it with his BPD, as its a fairly recent diagnosis. It's been an emotionally intense few weeks but while me and his FP have been supportive, he's still convinced his FP relationship is ending. Because he is devoting so much time and energy into his FP, I am being pushed away and this is putting strain on our relationship. We barely speak, he sleeps most the day til I wake him up at lunchtime, then we spend a couple of hours out shopping or doing errands, then he'll go for a lie down til tea time. Evenings after the baby is in bed are spent with me watching TV or reading while he sits with his headphones on either messaging his FP or moping because he isn't. I tried to explain how rejected I feel but it falls on deaf ears. I had a milestone birthday recently that he barely acknowledged. I don't know how much of this is his BPD or if our relationship has just ran its course. He's been going to therapy for years now but has only recently started working on his BPD, but even then he says he doesn't really try at the treatment, he just 'goes through the motions'. I can't really turn to family or friends as they don't understand BPD and will just cause more tension.

TL;DR - I don't know if to stay with BPD partner of 13 years who regularly pushes me aside for his FP relationships.