- And tell them from me that Healing Sex is not legitimate medical procedure. —Nurse Jennifer Robinson, during the 2008 Mary Sue Invasion.
The idea is basically that Twu Wuv and 'hot secks' can heal all wounds, make angst go away, and provide a satisfying conclusion to a hurt/comfort tale. The fact that, if you suffer from psychological issues, abandonment issues, or eating disorders, or if you've been injured or raped, you're unlikely to want to have it away with someone—even your Twu Wuv—seems to escape most badficcers.
Healing sex can be found in Suefics, slashfics, and almost any story with both romance and angst tags. It is good friends with dubious lube, rapefic, and Stockholm syndrome, and any combination of these dire Four Horsemen of the Badfic Apocalypse may be found cavorting together in blissful ignorance of the processes of romance, psychology, or legitimate medical procedure in the Real World.
In some few continua, healing sex is a real and valid part of the world, but these cases are few, and are very easily distinguished from charge-worthy healing sex by the absence of Twu Wuv (though True Love may well be involved).