In mulling over a situation in which one of my friends has found himself, I'm forced to consider the dangers of nostalgia.
I think there's a moment in everyone's past to which he or she can point and say, "Oh, I was happier then, or I miss this person, or I wish I had done X,Y, or Z differently," and I know I'm kind of the queen of that. Unfortunately, this wistfulness can either lift you up or drop you on your butt like a hod of bricks.
Sometimes, no matter how much we hope or dream that we can return to our first love, or to the One True Love of our lives, and it pains me to no eternal end to say this: it really isn't meant to be. Somebody could get hurt, and that somebody may not be the person at the center of it. We're in our forties now- there are children, and in a few cases, grandchildren. There's huge potential for collateral damage. In the end, the warmth and security that we craved bleeds away into a tangled mess, leaving our most cherished memories as burnt offerings to reality. We all want to be wanted, needed, and loved. It's a basic desire...but there are those who would lead us, against our own better judgement, into horrific folly. We have the power to stop it, or once engaged, end it, but will we? Hope can be a dangerously blinding thing when it's misplaced.
In the end, we ultimately have to make our own happiness- or misery. Best not confuse the two, or keep them running along separate and distinct tracks, lest their intersection be our undoing.