So i recently started to go down on my girlfriend. She really likes it the first few minutes, she tells me it feels reaally good! And i know because she starts tensing up and grabbing at my hair, but after a few minutes, she stops all those reactions and tells me that it doesn't feel AS good anymore. I spend a REAALLY long time warming her up, and i know she didn't orgasm. But after a few minutes she just tells me it doesn't feel good anymore. What is happening