She says that very early and it explained why she "prefers" that(because Shar forbids shit, she has no choice). She is not liek that in her selune path, everything about her selune path romance suggests love and commitment. I guess DJ Shadowheart breaks up with you ne matter what on Shar's demand. It's is reflected in her epilogue pretty well.
"What can change the nature of a woman?"
See, this is one of the parts where that whole Shar subplot starts loosing me, and it never gets addressed. It's very much a failing of "Bioware writing", and seemingly also of what Larian does (or strives to imitate). Intriguing concepts don't exist to be explored, but just as a curiosity in a story that does not truly care. Shar is evil, Shadowheart was brainwashed, let's move on. Nature vs. nurture ... you want to talk about this game? Nope, Shadowheart was brainwashed, let's move on. Okay, but is she still into whipping me? Game? Game? She killed and tortured people!
The point of this slight tirade being: Who is Shadowheart really? She is very kinky throughout most of the game. Are we to believe that this was the result of Shar's brainwashing as well? Should we just arbitrarily group all her pre-revelation traits into the "Shar" and "Selunite" baskets, depending on what we consider "good" or "bad". Did her whole personality suddenly change? How does that even work?