The "left a day early" thing is exactly why you gotta talk money before the trip, not after. I had this happen with a beach house a few years back, buddy bailed on night three and thought his total should drop since he wasn't there. Nope. The room was booked and paid for either way, his absence didn't save anyone a dime. Split it by nights you reserved, not nights you actually slept there. If the total was 310 for the whole stay, everybody owes their share of that full amount. Him leaving early is his choice, not your discount to eat.