I need some outside help!?

I've been dating this girl for about 2 mths now..everythings ok I shuld say we light weight fight a little over small things really...like her not being able to talk to me far as telling me how she feel...see I even asked her what stand out the most when we have ??, so I was really trying to find out what I do that kame her say ooooh my god...she can't tell me so I said I must not make u feel like that...she said I do she just lke everything...that gos back to her not being able to open up to me..so I dnt know..but this is my problem are life is great..no problems but when im havein wth my new gril I always catch my self with thoughts of my ex.im not sayin I see her face when we F***ing but after the fack..I don't know why tho...so I guess I need somebody addvice on what I shuld do? Or why its like tht?