This may or may not be a relief to her, because it does not sound to me like she made that choice consciously, until Xue could find his own strength to handle the problem himself.
So there was some need on her part to rescue and protect. And if that role is removed... it will cause a hole in her identity. She will seek to fill it. If she is doing all the unconsciously, she will fill it any way she can... and that may include negative ways.
This is absolutely a possibility. I was guessing it might be a relief for her due to Xue's description of their issues. But you are absolutely right to not assume that it will be a relief. Or even if it is a relief sometimes, that doesn't mean that she will feel okay about it all the time. So I should have said "might" be a relief for her.
I'll be interested to hear how you look at the feminine and how to accept it. I've never struggled with accepting it although being an engineer and growing up as a tomboy people may not initially realize that I am very comfortable as a woman.
But what is happiness except the simple harmony between a man and the life he leads? ~Albert Camus