Force relations was a power used by Luke Skywalker and Big Red after their mission to Nirauan. The Force practically, err, forced them to learn about it. It allowed two individuals to commune telepathically to enhance their intimacy while having relations. Even after they hit their tenth anniversary, having relations was pretty much all they did while the Yuuzhan Vong were invading. Some time during this, Ben Skywalker was born.
Luke misses Force relations. A prosthetic hand doesn't feel as good as the Emperor's Hand.