Isn’t it amazing how one little thing can “ruin the entire day”? My husband is like that too, and unfortunately life is full of “little things”.
What has helped me is realizing that when he starts down the path of dysregulation, the best thing for me to do is to not try and fix things, just let it be. He’s more likely to reset emotionally if I don’t try to soothe him or change his mood.
People with BPD have a deficit in self soothing skills, something most of us learned as young children. They can learn to do this, but it is not our responsibility to try and fix them. The best we can do is to be a good role model for them and manage our own distress.
We have a great library of videos and articles and here are a couple that might be useful:
https://bpdfamily.com/content/ending-conflicthttps://bpdfamily.com/content/what-does-it-take-be-relationship