BPD boyfriend

Hi, my boyfriend of 4 years has borderline personality disorder. I try and be as supportive as I can when he has an episode but I have no experience of this disorder and I sometimes think I’m not doing the best thing for him. He refuses to open up to me about his triggers which makes it even harder, I feel like I can easily unknowingly trigger him as I don’t have a clear idea of his boundaries. Recently it’s become obvious that my family are a trigger for him, whenever they ask to visit or I want to visit them, he immediately has an episode. I think it is just the social aspect of spending extended periods with my family and the pressure of ‘having it together’ for the whole visit. Whatever the reason, I’m beginning to wonder if we can really continue with our relationship if my family is a trigger for him. I’m very close to my family and like to see them often. I feel like I’m missing out by not having a boyfriend that can enjoy time with my family. Holidays and Christmases we’ve spent together have been very strained. I wonder if I can do anything to help his relationship with my family so that our time is enjoyable or if this can’t be fixed. I love my boyfriend, he’s my best friend but I feel like we can’t continue as we are. Any advice would be so helpful.