|Because what's happening now with Ren is worse than when Shou forcibly stole her first kiss in front of everyone and then laughed it off as a joke? Or when he used and cheated on her? Yeah, okay.
Kyouko actually likes Ren, she's only uncomfortable because she's inexperienced and because she's afraid to open her heart again.
And Ren isn't forcing her to do things she is really uncomfortable doing.
Spoiler (mouse over to view)
She's also walked in on him in the shower without any prompting from him. She was given opportunities to turn down the job of "babysitting" Ren, but she didn't because she has pride in her acting and because she truly wants to spend more time with Ren and get to know him better.