I disagree with the use of the word "rape" in that case. He could have tried to take advantage of her weakness without physically overpowering her. Now if we include in "rape" the idea of taking advantage of a person who is emotionally struggling in order to have sex, then she raped him at least once when she cheated on PB with Bojack. He had sex with her because he always had some kind of crush on her, because he is a sex addict, and because he thought that it actually meant something to her, surely someone good and righteous like Diane wouldn't cheat on her husband unless she was ready to end the relationship with PB and get with Bojack.

So if we consider it would have been rape if Bojack had taken advantage of confused Diane when she crashed on his couch for a while, then surely she raped him when she cheated on PB with Bojack. Otherwise it is a clear double standard which mostly implies that women are not as responsible as men for their actions.

You do make a good point about Bojack kind of guilt-tripping Diane on that phone call story but the line is often very thin between being selfish and trying to protect yourself from a toxic person. Since she never really tried to protect herself from super-toxic Bojack in the past, what she did at the end of the show was basically telling him that despite their history of supporting each other and hurting each other, now that she is better and despite Bojack trying his best to improve, showing some results, but then having his world collapse around him, she did not care about the friendship anymore and ended things unilaterally and selfishly.