Used to describe the situation where someone works on something they like for so long that when it comes time to enjoy the fruit of their labour, they're now sick of the object of their passion.
Like how a man studies to become a gynac so he gets to touch pussies all day but now that he is one, after a whole day of handling pussies he doesn't want to touch his wife and just wants time away from pussy.
She's suffering from a bad case of gynac syndrome