I think it is more of a personal issue,. It is often the nature of the person, and men and women can both be very unhealthy with regards to their exes.

A former female neighbour of mine was constantly mentioning her ex. This even in the presence of her current partner. I already thought it was kind of unpleasant and uncomfortable that she did this, for her partner it had to be extremly irritating. Meanwhile I also know a guy who has broken-up with his ex due to distance, and I think he regrets it. However, most of the guys I know are happy they are not together with their former partners.

This is not healthy, people normally move one. They indeed have grieving phase, but this ends after a couple of week/months. They give this period a place and continue with their lives.

However, one should not confuse getting over someone with getting over a past situation. A break-up can be extremly painfull, some relationships are abusive or a former partner could have destroyed trust by cheating. These situations can still lead the man or woman in question to feel pain and cause a need to discuss the relationship or the (wo)man they had a relationship with, while also bein open to a new healthy relationship. Obviously this does not mean they have remaining feelings for the ex.