Ungrateful partners don't see your sacrifices. They only see what you didn't do.
No matter how much you give, they'll still find a way to make you feel like it's not enough. If you keep bending yourself to please someone who only sees your faults, that's not love, that's being used.
If they can't see your effort, maybe you're just giving your best to the wrong person. You deserve someone who appreciates your effort, not someone who just counts your flaws.