I feel for your boyfriend in this situation, to be honest. I don't consider fetishes to be a bad thing, and furry porn is a thing that many people enjoy. Cartoon porn is another. I don't think this would require therapy of any sort. What he needs is an accepting partner. I also don't see anything wrong with watching porn. If this is something you can't handle, then it means you're not able to accept all of him. For his sake and yours, I'd advise you to figure out your limits sooner rather than later, because this fetish won't just go away.