1) Give users the option of posting it to their walls anyhow. Suffice it to say that I think you've thought this one a step or two farther than a significant portion of your users have. More broadly, very few social plays have failed because their users were just too darned smart.

2) If you don't want to have the difficulties associated with getting immature introverts dates, could I suggest doing something more important than getting immature introverts dates? I say this as exactly your target user for this, just older and (hopefully) wiser. If you're committed to doing social software, how about making something which people are proud to say they use or where the viral channel is built into the core experience of using the application? If you're flexible on what you're going to spend the next period of your life building, how about something which makes the world substantially better?

P.S. If you care, more than anything else, about doing right by the users of this application, you should say: "OK, here's what you should do: TELL HER YOU LIKE HER. We're not going to do the allow-you-to-wistfully-stare-out-window-while-avoiding-rejection thing because, honestly, we'd be selling you a fantasy which is directly against your interests. TELL HER YOU LIKE HER. You know how many people get dates because they use crush apps? Almost no one. Seriously, we could show you numbers. They're pathetic. Almost everyone who gets dates gets dates because they ASKED SOMEONE OUT ON A DATE."