The invitation, reformulated

I've got no problem with the fiction that I can visit someone anytime, which is how I believe most of these invitations are meant and perceived. To me a real invitation goes something like: "Why don't you come down in springtime when the calla lilies are in bloom?" To which I respond, "Sure, When's prime blooming time?" To which the inviter says "April 15." I respond: "I'll be doing my taxes that weekend. How's the week after?" And so on.

But what if the inviter doesn't know the rules?

A casual acquaintance invites you over for an unspecified weekend sometime in the future. You agree, though no plans are made. A week later, casual acquaintance calls to ask what time you're coming. You express puzzlement and say you're not coming. Casual acquaintance demands to know why you're not coming that weekend and gets upset when you suggest a date a month hence because "We've been planning this for ages."

If you're smart, you bow out completely because the casual acquaintance looks to be developing into a stalker. But that's just my opinion.