I have been dating this great guy for three months

Hi,
I have been dating this great guy for three months. He's someone with whom I could see building a life. We're both older (mid-30s and early 40s) and have a better sense of who we are and what we want, as well as baggage. Both of us have had serious relationships. In his case, it's an ex-wife of seven years who left him after multiple affairs he knew nothing about at the time.
Understandably, it was heartbreaking. He has taken five years working through it and feels like he is in a place to try again. However, the ex is still around in spirit -- the house they bought, fixtures she selected, and pictures where she's not visible but somehow has a connection to the subject. We talked early on because I was worried after she somehow was mentioned in every date. She's a huge part of his past and I don't want to discredit her role. The references are always devoid of emotion, usually just made in context as he shares stories from his life. Alas, her name still comes up in almost every date. I don't know what to think. On one hand, it doesn't bother me because I really do sense she is a part of his past. On the other hand, I find myself wondering if I would want to build a life around these memories. I'm not sure what to think. Is it normal to frequently reference past loves, even in an emotionally-neutral context? How do you know when someone has truly let go?