The first VGMV ends pretty happily, the 2nd one not so much.
From the Nana and Wolfs Rain soundtracks; "Kuroi Namida" and "gravity"
Has metal gear solid: The twin Snakes, Metal Gear Solid 2, 3, and 4.
The Boss/The Sorrow
(I know some of you may be thinking "bleh" at that last one, but remember that they aren't related by blood OR marrige anymore. Plus, it was very one-sided, Otacon was never able to see her as a woman.)