Can animals choose not to mate or experience repulsion by mating acts?

This has me curious. Is this whole mating thing some sort of concious choice? How common is it for animals to find mating repulsive and refuse to mate at all or again? I ask this because I know alot of humans who say it's a choice if they want to mate or be celibate and many find this whole act repulsive and do not wish to partake.