Your situation is similar to mine - although mine is English (when she finished Uni she went home, 200 miles away) - in that I absolutely adore her and, currently, want to spend my life with her. She is great. But I've yet to live with her and until I've done that, with success, I don't think I could consider marrying her.
Perhaps I'm applying too much 'common sense' to a situation where there should be none.