If you loved her then you will never stop thinking about here. That does not mean you cant love someone else and think about here even more. I think there is a movie on that with Jim Carey where he and his GF has their memories removed of their relationship?
I still think about my 1st GF who I dated back in 1981 - 1983 almost daily. I still think about my last real heartbreak girlfriend I dated 2005 - 2006 in Thailand.
I think it's pretty normal.