There's also a tendency for rape to be handwaved within its own canon in a way that murder may not be -- which of course comes back to societal attitudes towards rape. I think that's especially true of rape involving drugs or other forms of coercion (as opposed to characters being held down and forcibly raped) -- in several of the above examples, particularly Regina + Graham and the Owen situation, I'm not sure canon itself recognized what happened as rape, and there's another example in Life on Mars where it's clearly rape that takes place but equally clear that it's not perceived as rape by any of the protagonists.

I think this is a definite factor in my own circles of fandom among fans who refuse to forgive various characters for acts of sexual violence. In both the canon AND among certain elements of the fandom, the character is easily forgiven and their deeds swept under the rug of collective fannish/canonical amnesia, so there's a reciprocal tendency to go But wait, doesn't anyone remember what they DID? It's not necessarily that rape is a uniquely heinous crime (not that I'm suggesting it isn't sometimes treated that way) but rather that this particular tendency to forgive/excuse/explain away rapists in canon and in fandom replicates a chilling RL dynamic that, as you said, a lot of us have experience with, in our social circles if not directly.

(And I say this as someone who really loves several of the above characters. It's not necessarily a dealbreaker for me, but it is for a lot of people I know, and I think it has something to do with this.)