SFGate.com has a gallery of Longtime celebrity couples then and now, although the pictures are actually presented Now followed by Then. But I do not want to quibble with that.
What I quibble with is the “longtime” designation. Sure, some of the couples have been together since the 1980s or 1990s, which is qualifying as a long time these days (he asserted, limping after his most recent triathlon class). But so many of the longtime couples here only became a couple during the last part of the Bush 43 administration.
Maybe that counts as a long time in Hollywood or in San Francisco. However, I go to church, which regularly celebrates 50th, 60th, and 70th wedding anniversaries. So 13th anniversaries of couplehood is a good start.
Since I mentioned it, here’s “Foreplay/Longtime” by Boston. Which runs almost eight minutes, but the intro part (“Foreplay”) is almost two and a half.