As an unwise frog of little brain it sounds to me like your psyche is taking a time out. Having survived the chaos of Christmas and not yet ready to take on the uncertainty of a new year. Everything is just shutting down needing a chance to revive.

As far as the sex part, I won't touch that with a 10 pole or a 6 ft russian. It actually sounds more the intimate bond that occurs when you care deeply for some one and the feelings are returned. It's as much the "soul mate" attachment as the physical sex part.

IMHO I think your "mood" would improve with a few good nights of restorative sleep. Naps don't count.

My little slimy froggy heart goes out to you. I've been there. It's not fun but you don't have the energy to do anything about it.

Here for you if you need me.