You’ve made us all think about this!
I’ve been thinking that it’s not really the part where she says to stop and he doesn’t–she has, at that point, consented. There’s this scene before that where they’re talking about what claims Claire has on Jamie and (…had to go find my Nook to quote this right…) Jamie says “you’re my wife, and if I want ye, woman, then I’ll have you, and be damned to you”. Then she gets him with the line about acting like BJR. That part upsets me, it makes me shaky.
But C is clearly just as possessive as J is, she just isn’t at this point in the series–since she’s still planning on leaving.