I'm really bad to predict what's going to happen too, and I had a similar idea about what Marian was going to do, but it turned out differently.

If she stays with Robin, Marian dies. I think her trying to let him go shows character growth.

Yeah I know. Maybe I just hope that she will stay with Robin because I ship them... lol But if Regina makes him leave her so that Robin saves his wife, than it's good coming from her, and I would be okay with that too. But I'd still hope that Robin would end things with his wife, telling her that he cannot fell out of love from Regina, or something along those lines. We'll see...