Kylo Ren can't show any weakness to the crew of Starkiller Base, nevermind let it slip that he is a human with sexual needs and a normal, unmarred face. So he decides the only way for him to get the release he craves is to disguise himself as a low-ranking officer or an on-base "comfort worker" and be treated like a nobody or a whore.

He didn't count on attracting the attention of General Hux.

Bonus if Hux really doesn't know who he is until very late in the game, but does pick up on some tell while they're intimate.