[He regards her carefully, ear twitching in thought. He really doesn't want to go through with this, but not for the reason she probably thinks. He needs her to understand so she can use that wish wisely...assuming it'd ever work.]

[He kneels down so he's on her level.]

My dear, please don't think me ungrateful. The reason I don't want to use up part of your wish is because I've received so many blessings this year both large and small. Far more than a sinner like me has any right to. I don't feel comfortable asking for more.

[That and he doesn't want to piss off the Creator or Whoever else might be granting him such boons.]