That's actually not very reassuring. You might interpret it as she'd be willing to sacrifice everything to stay with him, but it could be just the opposite. She might mean it to be reassuring, but that doesn't mean that's the only way to read into it, nor that that will be how he hears it. He's insecure, so he needs more definite wording in order to understand her intentions, otherwise he's going to be taking everything in the worst way.