Fiction is fiction. This to me is a guiding principle, and something I believe should never be forgotten when it comes to writing or roleplaying. Reality and fiction are two separate things, though fiction [u]can[/u] comment on reality, asserting [b]reality[/b] as being analogous to [b]it[/b]. The fiction never ceases to be fiction or claims itself to be real (bar a few particular genres whose characteristic is none other than making such a claim) but in taking itself as a serious approximation, it can make claims about how reality is. 

Conversely, this also implies the opposite- when fiction does not make such an assertion of realism, I find it to be nothing short of absurd to thrust expectations of accuracy or of being representative of reality onto it. Of course, the question of [i]tastefulness[/i] is important in any case, but that is far more subjective than a standard one can govern themselves by. But whether making a comedy, or a serious exploration of something, or even just employing something for a darker setting, I don't believe any particular taboo should be considered strictly off limits for every story. I believe the important question is whether it fits that narrative, and that the more seriously a story takes itself, the more it incurs the responsibility to take the matters it deals with more seriously and faithfully as well.

This to me, is what makes the difference between that cliché romance plot about a kidnapped princess, or a fairy tale like [i]Beauty and the Beast[/i] and a plot focused on a psychological deep dive of Stockholm Syndrome. It goes beyond even this though- RP can allow one to explore fantasies, and things one couldn't- and shouldn't- do in real life. A thread in another site I am on even brought up the topic about people enjoying plots about kidnappings and abuse, and a common response boiled down to saying to that they knew it was wrong or dangerous or unhealthy in real life, and that in itself was why they wanted to engage it through RP.

In the end of the day however, like everyone and their grandma have said, you gotta respect what your partner's comfortable with and that really is where the line in the sand is ultimately drawn, what people are willing to do with you. But this is the practical level of the compromise and I don't necessarily believe it satisfies the question of "should" by itself.