
I'm glad you have found us on the internet, yet I'm sorry for the trouble that has you searching for answers.
I want to assure you this is a safe place to ask questions and gain understanding of confusing and troubling behaviors that you are struggling with in your relationship.
I've read your post and I have a few follow up questions and a few initial thoughts.
Before 8 months ago, were there any weird behavior things in the r/s (how long have you been together?) Such as "accusing" you of not supporting him and that kind of thing?
Can you briefly sketch out the doctor visits he has had and what things have been "ruled out" and if that is definitive or just "pretty sure"?
Has a sleep study been done?
I'm going to suggest your first reading.
https://bpdfamily.com/content/communication-skills-dont-be-invalidatingbpdfamily has a number of articles that help members understand concepts that are critical to improving a relationship with a pwBPD.
Your first big question: How would that article relate to your discussions about whether or not he has ALS?
Thanks for caring enough to find us and to search for answers. I'm going to guess he doesn't see you as caring much at the moment (given his accusations of non-support).
For now, please keep your thoughts about BPD and other "diagnosis" to yourself. There may come a day when it is wise to share, for now... .let's work on educating you some. How does that sound?
FF