"Married people who contact lost loves often say they just 'want closure'. But there is no closure: the old feelings always come back".
(Nancy Kalish, Ph.D., http://www.lostlovers.com/)
For better or worse, we live in an age in which it's relatively easy to track someone down. Anyone with imagination, patience, and Internet access can learn more about someone in ten minutes than the famous literary detectives of the 1940's could learn in two weeks. Most of us have probably "googled" old friends, lost relatives, and people we used to work with in the distant past. It can certainly be interesting to see what people are doing now, or where they're living, and sometimes it's tempting to go a step further and contact them. And of course, some people invite others to contact them, through their membership in classmates.com or similar sites.
All of this is usually harmless amusement, provided, of course, that one doesn't become a pest or a cyber-stalker. But one category of sleuthing and reuniting that should be avoided at all costs is tracking down old lovers, if either or both of you are currently married.
I've known a fair number of married people who have contacted or been contacted by ex-lovers, and they all tell a similar story. The first contact is typically an innocent-sounding e-mail that explains that he or she stumbled over the other person's name while doing a totally-unrelated search, which of course triggered a curiosity about what the person might be doing these days, etc. If the response is at all encouraging, the next e-mail will usually be a bit warmer in tone, alluding to happy memories and suggesting that it might be fun to meet for lunch sometime soon. ("Well, why not? We're just friends now").
The lunch always seems to be at a nice restaurant, on a day when both parties can afford to linger a while. ("We have a lot to catch up on"). After the usual exchange of information and life-events, the conversation invariably turns to their past relationship, or at least the parts that they prefer to remember. The longer the conversation continues, the more each person is likely to start feeling those old feelings, the kind of feelings that seem to be lacking in his or her marriage these days.
This is dangerous territory. What is happening at that lunch, and at any subsequent lunches or meetings, is a battle between illusion and reality. And illusion will always win that battle. I say "illusion" because, with a lost lover, we're not looking at him or her as a real person (the way we look at our spouse) but as an embodiment of a happier past. We conveniently forget that there were good reasons why the relationship with that person ended, or we gloss over those reasons by believing that we must have made a mistake in breaking up; that if we had just given it a little more time we would have gotten it right.
The reality of your current marriage may or may not be a happy one. There may be problems that need fixing. But they're not going to be fixed by escaping into the past---a past that was idyllic only in your imagination---or by forcing your real-life spouse to compete with an illusion. Even if the contacts with your ex-lover never lead to an affair, they're likely to engender an increasing dissatisfaction with your marriage, and even a resentment of your spouse for depriving you of the life you think you were meant to live.
I'm not saying you should accept your present reality without complaint. I'm saying that the way to improve that reality is by recognizing problems and doing something about them, not by embracing a fantasy.