Bf help

I’ve been with my bf for over 3 years. In the first year of our relationship he seemed depressed so I encouraged him to go to counseling, where he was diagnosed with OCD. Flash forward to now and things have been going downhill again. He doesn’t take his meds and won’t take action to go back to counseling. He shuts me out constantly and I’ve tried every method of helping him. I want him to be happy and know that he can talk about anything with me, but he literally gets so down that he won’t speak to me. He just sleeps for hours on end. What should I do?