either you're going to have to wait and hope they grow or hurt their feelings a little. idealizing someone commonly includes assuming they're just modest as hell, so unless your friend's done this before (or can look at their own thought processes objectively, which doesn't sound like the case), you're going to have to do something to deviate from their current impression of you.

clearing the air and taking a little break might be good for both of you. i would go with above anon's suggestion, but substituting 'gentle' for 'firm'.