I think my girlfriend's depression is going to destroy our relationship.
Why do you think her depression is going to destroy your relationship?
She never wants to do anything and always wallows in misery.
I understand that it's difficult for you, but it's even more difficult for her. I think you should encourage her to seek help through counselling, and try to support her as she tries to get well.
I still think that she needs to work harder but I will try some of your advice to try to help her more.
I think that is a great idea. I am glad to hear that you think you can more supportive to your girlfriend and I think that will be very helpful.