I'm pretty sure my cat is sentient, but I don't take that to imply that it can consent to sex, since its spoken vocabulary appears to be limited to "meow".
Male cats develop barbs on their penii after about 5-6 months. Female cats don’t ovulate before copulation. It is painful every time and the female cat can’t escape the male cat who detects her estrus. When a female cat is in heat, she can ovulate as many times as a male copulates with her which is why a single litter can be fathered by more than one tomcat.
Why cats evolved this way in nature, we don’t know..but rape is not uncommon at all in the animal kingdom. Nature is brutal.