...is that it is a reference to something alluring and almost even exotic that Frenchwomen are seen to possess in the imagination at that time. Again, I have nothing concrete to back it up, but I just think that Mary views Frenchwomen as being more captivating than Englishwomen.

Also, I think it implies the sheer numbers of women who have sought after Henry and failed. When she says, "All that English abilities can do has been tried already," I think she is saying that Henry has broken virtually all the hearts in England and there aren't any left to try for him. ;-)