It does take time for them to get over the OP...I know my H was home for about 9 months when I accidently discovered he had emailed her again...actually I found out about the emails about 8 months after they were sent/received...there was no evidence of more so I let it go for a bit...then when I asked he admitted that he had contacted her...I dropped it when he reminded me that he loved me and was no longer contacting her or thinking of her...when I read those emails I realized that was his way of making sure she was okay...the nice guy that he is/was/is I think he needed that for closure...
It takes time...what matters most during this time is how things are between the two of you...I rarely questioned my H about what he was doing and where he was going...I didn't feel threatened for some reason...when I did feel doubt I would ask him...or we would talk about my feelings...he seemed to appreciate that I wasn't accusatory and snoopy...I think he liked to know that I was able to trust him and for the most part that I was/have been able to leave the past in the past and move on with him...
I hope this helps you...take care...piecing is hard...Lin