Depressed people have cycles of depression. She'll be normal for a while and then depressed for a while. She's just always going to be this way. It's your decision whether you want a person like that in your life or not. But if you decide that you do -
learn up on behavioral treatment for depression.
When she's feeling down remove your expectations of her.
the thing she likely wants to do most is curl up in bed with all the blankets. Do it with her.
Encourage her to be easy on herself - the worst part about being depressed is the crushing guilt and feeling of uselessness.
Don't let her know that you wish she'd get better soon - just be there to support her until she does. (Again the guilt thing)
Take her on walks and to do quiet calm things with her like sit at the park or for drives in the country to look at the stars. Nothing too stimulating. People get emotionally exhausted very quickly when they're depressed

>>17332233
get a new girlfriend

>>17332233
women are only happy when they're unhappy.

dump her and find a new bitch.