In love but don’t know how to manage

Been with my bf for a few months know I accept him for who he is but there are times where he shuts me out and he doesn’t talk to me for days and I know that it’s probably a depressive episode due to his bipolar disorder and I want to help him in anyway I can but I feel like the only way I can help him is by giving him space, but at the same time I feel isolated from him and this makes me sad and I overthink which is one of my mental health problems and I always feel like I must have done some thing or I’m a problem and my brain goes to worst case scenario. Any advice ?