In reality there's often issues of manipulation into "consent".

And if the relationship goes bad you lose a family member, not just a lover.

Is it always wrong? To me, unquestionably no (consider my example.) Is it risky? Yes.

I'd agree- I think the analysis I was referring to believed that analyzing a taboo makes it no longer useful as a shortcut. Guess that didn't come across enough for anyone to offer a refutation.