I'm so sorry you've had to go through this.

I'm bipolar, and yes, we are intense and passionate and too quick with our emotions.

That being said, him off his meds and receiving no treatment isn't a good thing for YOU. If he wants to play that Russian roulette with himself, that's his decision.
It wasn't the right decision to make regarding you, however.

Even though you care for him, go to sleep every night knowing he made his decisions (the first NOT about seeing someone else, but about no treatment) and it's healthier for you that he isn't in your life right now.

If you ever want to pursue a relationship with a bipolar, though, my other piece of advice would be to never, ever try to "test the waters" by saying you've been asked on a date or flirted with or anything like that. Speaking from my own experience, there is enough trauma and drama going on in my own head- if someone brought that kind of stuff up, it would push me over an edge too.

Live and learn. Cry and then get up and go to work. You'll be ok and I venture to say better off without him. Best wishes.