Welcome back, Brad! Glad to know you had such a good time. The last night of a cruise is always a sad affair, with people needing to go pack, seeing luggage outside cabin doors, and everything winding down. Plus, re-entry and reintegration into real life is awful!
The good news is that the best known cure for end-of-cruise depression is a little pill called "booking your next cruise." It works every time, there are only happy side effects, and you can repeat as often as is necessary. Insurance won't pay for it, but it's money well spent. Who can put a price on joy and peace of mind? :)