My Wife’S Lover (2015)

In terms of sexual preferences, Joon-ha likes normal things, but her girlfriend So-jin likes to be tied up and beaten. So-jin was worried about her own sexual taste because Joon-ha teased her every time, so she complained to her friend Mi-yeon. She finds out that the man Mi-yeon is currently dating, Do-joon, has a similar taste to herself, so So-jin suggests to her friend that they swap partners.