[bacro]

The question is: What if the depression she has has a cause that can be curable 100% and she can have a very happy life, would she still want to do it if she knew that?

I am not sure that we "should be free" to end our life as you say. Sure, we did not have any say about coming to life but I think that if you don't have any incurable disease that causes you significant pain, you can always find something that will make life worthwhile. Unless you are born in Northern Korea or some country that restricts your freedom.