1: What? OP said bipolar, not BPD.

2: Are you aware that members here have BP and BPD and might find your reply insulting?

Anyway, back to the OP.

Sounds like he's in the midst of an episode atm, so you have two choices:

Alert the doctors (and risk him being upset with you) or stand on the sidelines and pray it ends soon...

My bf used to disappear when he got severely depressed, as a borderline / bipolar myself, I found it agonizingly nerve wrecking, but my excruciating patience paid off and now he feels safe enough to let me in to that vulnerable space.

I suggest that once your man lands, have a talk with him wrt what needs to happen during episodes, what role it is you can play.

While I don't like the above posters berating tone, I do agree with one thing he said though.

If this man doesn't want help, whether that be therapeutic, psychiatric or self help, you can't make him get any.
Well you could give him an ultimatum, but that rarely ends well for anyone.
And if we don't manage our mental health, things can get ugly and people get hurt, whether we mean for it to happen or not.
So I would give serious thought to whether or not I could / should / would stay with someone who's life becomes unmanageable in a blink of an eye, because as you see, it affects everyone, not just those of us with acronyms next to our names.