Eh, commendable effort from the poor magician to try. He did say he intended on finding her before she sacrificed herself, just that he apparently didn't find her in time.
Of course, she wouldn't even have accepted before that point, being so focused on being the pride and joy of her family. So realistically this was the only chance he had to take her. Again, too bad he didn't find her in time.
And now that he gets a chance of getting what he wants, of course he'll try what he can. It's not like there's anything else he wants to do, so far as we've been told RN.
Nonetheless, big rip to him for fighting a dragon THAT CAN CORRODE ANYTHING LIVING THAT TOUCHES HIS BODY (and hasn't been coated in his saliva first or has magical properties to resist that, that last part since the dryad didn't die to his touch). If anything at least he'll die understanding that she'll be with someone dependable to take good care of her.