No it's not all that strange.
Most of us had our "first love" in high school or college.
As the years roll by and we've had to contend with jobs, marriage, children, and numerous other responsibilities.
It's easy to look back at time when we loved someone and were free of other worldly pressures. Our parents provided all of our essential needs which freed us up be "all in" for a romantic adventure.
During our youth we're also "unrealistically optimistic" about the future and everything is a (new and exciting experience).
To illustrate just how immature most of us were we honestly believed we had found our "soul-mate" at age 16, 17, 18, 20 or whatever age BEFORE we discovered ourselves!
We also believed the traits our ideal mate had at that age would be the same traits we'd want in a mate twenty years later.
Most of our breakups with a "first love" usually involved someone moving, going away to college, or a painful betrayal.
Either way many of us never allow ourselves to be "all in" again. We learn to be slightly cynical about love and not simply take our mates at their word until they've proved themselves.
Even if we find "real love" later in life it's not the same as when were in high school or on a college campus where we had more free time.
Dealing with a demanding boss, stressful job, paying bills, raising children, and many other things can make you recall a time where life was simpler and love was easier.
With the invention of the Internet and social media sites people not only "wonder" what their first love is doing but they actively see if they can relocate them! (Google searches, LinkedIn, Facebook, Classmates.com and the like) have put people back in touch with exes and sometimes affairs have taken place.
Usually it "innocently" begins with just reaching out to say "hello".
An exchange of contact information takes place (behind the back) of both of their spouses or current mates.
Next comes the (what have you been up to discussions), followed by the "memory lane" discussions, talk about other friends during that period, and eventually one or both people confide that their present relationship isn't "a bowl of cherries".
Note: All these emails, texts, and conversations are "secretly" done behind their current mate's back. Eventually there is "emotional cheating" or physical cheating. At some point they get busted.
"We never planned this. One thing led to another..." LOL!