Mind blowing sex huh? Then an emotional blaaah time, that was buoyed by P, then another clunker on down?
Could it be subdrop? That's what flags to me.
The endorphins from the mindblowing sex experience leaving your system and leaving you sensitive and all blah. I know this article comes at it from the kinkyside of town and not the polyside, but the body hormone stuff of sex (of any flavor) is real. Body is body is body.
Know this, so you don't have a premature wigginz on your polypeeps. Thank them for the metasex soooo wonderful it puts you up and over the edge and gave you the mega sex hangover.
I don't often see it written from the "polydrop angle," so my apologies I could only find "kinkydrop angle" for you. In a rush here so... I leave you to google better.
But the neuroscience of sex and the hormone load is fascinating to me.
Dealing with Subdrop
As an aspect of aftercare, we should also note that a phenomenon known as subdrop often occurs after a good scene. This can occur quickly or may not appear until several days later. Subdrop is a state of depression and moodiness that often occurs after a heavy scene or where the submissive is away from their dominant for an extended period of time. It is the result of increased prolactin and cortisol levels. Aftercare isn't something done only immediately after a BDSM scene, it should be something the Top should do in follow up with the bottom for several days afterward. This should especially include phone calls to check on the bottom when personal contact can't be made.
For methods of countering the effect of subdrop, please visit Ten Ways to Fight Subdrop.
You can google others.