Unfortunately, reminiscing with people who you were in a relationship with in the past should be avoided, especially if you are currently attached.
I have a small handful of girlfriends with whom we openly talk about some details of our current relationships. The one thing that constantly comes up in conversation is how annoying it is when the past deliberately brings up events in which to reminisce about with your current partner. "Oh, do you remember the time when we did..." or "Driving by this place always reminds me of....". Being someone who used this routine many moons ago to win back an ex, I am fully aware of what is going on. Of course, your partner usually has no clue what is going on, chalks it up to the 'good ol' days' and will even go as far as sticking up for the past.
These acts are committed without good intentions and are selfish; they leave you drained and wondering 'What if..'.
What if the grass really is greener on the other side?