I may be the only person who thinks this, but I don't see her as waiting for him in any way. I don't think she wanted to marry him; I think she knew she had much more power as his mistress (girlfriend? I'm not sure what term to use) than she would ever have as his wife, and of course she witnessed (and participated in) his abuse of JD. I think they (FD and MT) are two cons running each other as long as it serves either of them, and I think either of them would turn on the other like a cobra if they thought it would halfway serve them. I don't see her wavering because of her daughter, or him, or certainly his children. I think she's as much like FD as she can be, and she's playing him