Say you message them on a Tuesday asking if they want to go for dinner/go see a film etc.
And they reply saying, "It's too early to say what I'm doing yet."
She doesn't have children or other commitments that I know of.
Don't see why it's so hard to commit to something 4 days away? It's not like I'm asking months in advance.
It just seems like she's waiting for a better offer first. Does it?