movie could've been better as a real bdsm movie

the movie was so good up til the moment where they are shown in bed together. it was setting up to be so exciting when i thought she would get spanked. then ends up, you never see any punishments at all. they should've just made the whole story about her working for the master then slowly the punishments get more and more sexual until the boss and worker roles are blurred and it becomes master and slave and the master gets to do anything sexual to the slave. the pain from punishment and the pleasure from sex are intermixed and the slave can't tell the difference anymore. she willingly is subjected to both.