Dear Miss Manners:
What's your beef with a cash bar at wedding receptions? Weddings are incredibly expensive, and a couple starting out shouldn't have to go in the hole for thousands of dollars just to throw a reception where Miss Manners and a bunch of other deadbeats can have unlimited liquor. I thought you were a classy broad!
If we should encounter each other at a wedding reception, then your first drink will be on me, and you can hustle the rest yourself! I DARE YOU TO PRINT THIS!
Suppose you go first and explain why anyone would want to stage a thousands-of-dollars event for people whom they think of as deadbeats, and why other people would want to attend the wedding of those who thought that of them. This will give Miss Manners a moment to think of a tactful way of saying that she does not care to drink with you.