So basically he told her "I don't love you but I want to marry you for power. In exchange, I'll also help you acquire your own power. You scratch my back I scratch yours." I mean, at least he's honest. And if she marries him she will have all the time in the world to find a way to woo him if her love for him stays true. Sure, he seems a little dangerous, and he's definitely the manipulative type, but he's straightforward with those he deems partners in crime so he has that going for him. Let's just hope he doesn't turn out to be a right bastard that stabs his partners in the back later.