How do I tell my girlfriend I'm a therian?

So, I've been seeing my girlfriend for a few months, and before that we were good friends. Before we got together I never mentioned I was a therian because I didn't think it was that important at the time. But now that we are together, and things are getting serious pretty quickly, I have no idea how to tell her, or how she feels about therians. Should I tell her? Or should I just not mention it? I really don't want to lose her, and she's a really sweet person so I doubt she'll think differently of me. But I have no idea how to tell her.