I have a guess that your girlfriend is depressed. She probably has some mistaken idea that she is just a burden to you.
You have a tough challenge here. If you crowd her, she could just get angry. But if you leave her alone, she’ll probably get more depressed. You need to find a way to strike a balance. Tell her you love her and are concerned about her. Let her know her weight isn’t an issue with you but her discouragement and sadness is. See if you can persuade her to see a counselor to help her get a jump start out of the depression and some practical help finding a job. Go to the appointment with her if she’s afraid and if she’ll let you.
Meanwhile, do everything you can to get her out of the house and doing something, almost anything, every day. The sneaky thing about depression is that it gradually gets worse and worse unless something is done to interrupt it. The less someone does, the less they feel like doing so the less they do. Next thing you know, they’re in the pits. If you can get her doing some things she used to enjoy, it could help turn it around.
I wish you well.