Post-scene plunge is a phrase used to refer to feelings of depression or let down following participation in BDSM activities.
More About Post-scene Plunge
Participating in BDSM activities causes feelings of pleasure and euphoria, which can make going back to regular life following such activities feel very depressing. The highs experienced during a BDSM scene are often followed by lows that bring with them depression, fear, disgust, or even remorse.