This only happens to my girlfriend. My cat (female 5 years old) loves her. My cat always comes to her to get pet. They lay together in bed, and a lot of times, the cat even gets under the covers with her. Lately, however, my cat will be sitting next to her in bed, my girlfriend is petting her, and the cat will start hissing, growing, then violently attacks and scratches her severely. A few hours later she is totally normal. Why does this happen? How can I fix it? Can someone please help me?