2. In the context of this anecdote, the issue was also (IMO) the relationship she had with Robin, and the responsibility she owed it.

I didn't think of it from this angle (tho' my post about the immorality of prostitution had more to do, I guess, with other posters judgment about it).

Your thought about Marion's responsibility to the relationship reminds me of a Victorian era argument used to explain why men are superior to women -- because men's morals were based on absolute values but women's morals were seen to change, depending on people and circumstances. (I don't know if I am describing this very well, hope you get my gist.) In this circumstance, Marion felt her first priority was freeing Robin, but (you're saying, I think) that the higher plane would have been to consider the abstract construct of the relationship. I don't know, does it fit?