I'd say it depends on how long you were together and how intense his feelings were back then. The circumstances of the breakup can be a factor, but they won't erase the real unforgettable times very rapidly. So I'd say yes, unless you were one of those on/off couples, he probably does - and maybe even somewhat at moments when he isn't alone. You can miss someone and remember them for a long time even if you may not have plans to get back with them. Sometimes we get out of relationships because things change. It doesn't mean we always regret that it started. They say don't dwell in the past and it's true, but you don't want it all to have been for nothing. If we try to wipe out everything that is behind us, we may not have much of our life that counts. So there are some memories I keep. I don't bring them to mind when I'm making love, but they're not gone.