Just be as loving and understanding as you can. Remind her that you love and care about her often and take good care of her. As someone that’s had severe mental health issues, I don’t expect my girlfriend to make it better. She does give me so much extra care when I’m struggling and it means the world to me. Because of how much she shows me she cares, when I hit low points and start to feel suicidal, I always come to the realization that I could never hurt her by doing something stupid like hurting myself.