Cas does care about Crowley; I think he realizes that sometime around s6, but to accept that would be to acknowledge that a lot of his actions are motivated by selfishness more so than a desire to do the right thing. The cognitive dissonance that causes, especially after TMWWBK, is why he convinces himself that what he feels for Crowley is hatred and betrayal - anything more would require a level of introspection and self-acceptance that he’s not prepared to deal with.
This is, in many ways, a result of the fact that he’s learnt how to be human from Dean, who has passed on his rigid, black-and-white mindset that for someone do bad things they must either be inherently evil or devoid of agency. There’s no space in Dean’s, and therefore Cas’, worldview for good people to simply make mistakes, so to keep himself from mirroring Dean’s spiral into self-loathing he must believe that he had no say in the events of seasons 6 and 7. Crowley never forced Cas to make any of the choices he did, only offered them up as possibilities, but that requires acknowledging the consequences of his actions, and it’s far easier to see a demon as inherently evil than to take the same view of himself.
