I'm puzzled by your interpretation and even the emphasis.

You and I both agreed the sister-in-law wasn't a lesbian. I was tempted to say the s-i-l had been a functional borderline who decompensated with the death of her husband, but Nancy points out that dependant personality disorder fits the description better. She needs someone to live for, and all the thrashing about is because of her desperation. I'd say that a cat from the animal shelter would be a better choice for this woman, but that would so get misinterpreted. That, and there's the risk she turns into a crazy cat lady....

(Actually, my original comment on the actress not being a lesbian was bringing up the question of whether gay and lesbian parts should go to only gay and lesbian actors, but let's leave that for another time.)

Take the situation with the gay man and his "girlfriend." Reverse it. The man pulls the woman into the back of the car, she says "no" and gets forced into sex anyway. In other words, they were joking about rape.

Some might argue that the gay man had an orgasm and thus it couldn't be rape, but I've had to explain to several female patients that having an orgasm does not make it any less rape. The gay son's attitude afterward is a reaction that a significant number of male rape victims exhibit. By saying "hey, I'm young and horny" they're able to take back some control at the expense of being able to admit to themselves they were violated.