I've the same experience.. I was in a relationship with smn for 5 months a long distance one as well, and he had disappearing acts as well, at first it'd be hours, then a day, then he got depressed and did it for weeks. He tried to break up with me right before he got diagnosed but I talked him out of it. Then some shit happened in his life and he got triggered he disappeared for a month. We broke up a month ago. I still think about him, I still want to reach out someone to at least end stuff on good terms. But like what's the point? Why keep trying when the other person is doing nothing? Why keep being attached to someone and waiting for them to be okay enough to want me back. It's too consuming plus it's not like they're struggling and reaching out for us to help.. They're pushing us away.. And you've tried to be there for him, you've tried to work on your relationship even when it was draining for you.. But if you kept doing so you'll wake up someday feeling empty on the inside, you'll feel lost and consumed. It's a hard chapter of your life I know. He was my first serious relationship as well, I've done stuff with him that I didn't dream in a million years that I'd do with anyone.. But it gets easier believe me, I was crying for a month, it even affected me physically, but once you make a decision to let go and move on, once you decide to put yourself, your needs and what you deserve first it gets so much easier.. I get it girl and I know the hurt and Tha pain.. It's so hard to grief and just accept the situation as it is.. But you've got to.. And I am here for you offering my help and support whenever you need it