Melody (1971) - a British movie starring Jack Wild, Mark Lester and Tracy Hyde. The soundtrack is all songs by Bee Gees (amazing).

I first heard about this film while reading an interview with Wes Anderson - it's one of the movies that inspired Moonrise Kingdom and you can definitely see why.

The best scene in the movie is the following one...
In case you didn't watch it (shame on you), the main character fantasizes about the girl he loves during a track meet while "To Love Somebody" plays in the background. At first I thought, "This is the most absurd thing ever," but then I realized that it is SO ACCURATE to the ridiculousness that is young love.  

When I played field hockey in high school and middle school I actually used to make deals with myself as I dribbled, "If you get a goal you'll get to dance with Brian at the dance." At night I'd lay in my bed, listening to music on my walkman and directing elaborate music videos inside my skull.

One of the more embarrassing ones: I'd listen to "Come What May" from Moulin Rouge... only instead of Nicole Kidman and Ewan McGregor serenading each other, I'd be singing the song with a boy in the middle of some dance in the gym. Romance.
See all the previous movie posts here.