Seems like this well known chestnut finds it's way into a whole lot of jam sessions. For us it's yet another example of the ubiquitous 1-4-1-5 chord pattern.
(If that's Greek to you then you can learn about the number system at some soon jam camp. We'll cover that and a whole lot more!
Notice the solemn and silent aftermath in honor of all those lost loves through the ages. (Winking emoji here)