Think of it this way: many people enjoy watching horror films, but that doesn't mean they'd like to be in a frightening situation, right? It's the same idea. It's normal to have different standards of acceptability between what you watch, what you imagine, and what you'd actually do.
I'm the same way. I watch plenty of porn of stuff I'd never do myself in a million years. I have rape fantasies, but I don't ever want to actually be raped (that would just be horrific). It's all about being grounded in reality.