After a spin-the-bottle session goes wrong in Bart's treehouse and Milhouse ends up kissing Homer the subject of kissing comes up and Homer confesses that Marge was NOT his first kiss (in High School). Homer tells the story of his time at summer camp when a younger version of him, Lenny, Carl and Moe. At camp Homer gets himself into a blind-date with a girl from the very posh girl camp and they end up kissing on their blind date.
But is this girl more than he knows. As soon as Marge hears the story she realizes that SHE was the girl. Homer is very happy to hear that but Marge becomes upset over the fact that Homer was the one that broke her heart over 30 years ago because he never showed up for the second date. Homer then explains that he couldn't make it because of an accident falling down the gorge and ending up in Fat camp. After escaping, he was too late to catch Marge and explain.
Marge however is still upset in the present day, until Homer produces a stone she gave him, proving that he did care.