I liked her... now i feel nothing..?

I was in a bad relationship with this girl, Amanda.I'm not gonna say why... but I felt nothing when i kissed her... so after a wile i dumped her and met this other girl named Brittany. I really, really liked her... now i'm with her and i feel nothing why i kiss her. But it feels... idk awkward in a way.. and i don't really like her that much... why is this? :/ Were great together.. just i don't feel anything when i kiss her.