They both have very odd ideas about what is and isn't acceptable, no set boundaries or safewords. It's been working for them, so far.

Kylo pushes Hux further than before during a bout of rough sex, and Hux drops like a rock into sub-space. One second Hux is as closed off to him as ever, the next he can tumble straight into this addled void where Hux's mental barriers should be. It freaks them both out.

It keeps happening.