Uhh I think he just didn't really want it in that moment? The translation of the novel I've read was kind of confusing but he said that he didn't want to get violated and stuff
And I mean, if he didn't want it, he didn't and that should be respected, but Dane influenced him with his pheromones and yea it ultimately happened
I mean, sure Dane was also heavily influenced by his heat, so ig he can't be fully responsible? But he did what he did and it was rape
Dane was acting even more aggresive and out of his mind than normal (ripping Grayson's clothes, jumping to Grayson's butt and dick while also use his pheromone to trigger Grayson's rut and stop him from getting away). Grayson might have wanted to sleep with normal Dane before but an under influence Dane who make him powerless is another thing.

I have a feeling the next chapter is gonna be wild...i hope I'm right. And I also hope it's consensual