Middling is the word.
Not sad. Maybe it is the rock"n"roll generation in me but I keep thinking that any minute it is going to take off.

Here is a sad one with a happy ending.
https://www.youtube.com/watch?v=btVGz294X0w

Gets to you every time, doesn't it!! Poor n.

Here is one that runs the gamut, sad, beautiful, uplifting.

https://www.youtube.com/watch?v=ZLoBWpiOczQ

This one is not dark but has a bit of a sad ending, which seems to make it all the more beautiful.
https://www.youtube.com/watch?v=cJ2gizaqVw8