My J/7 support must swing in the direction of losing Seven over Chakotay dieing of a broken heart (which actually seemed unlikely to me).
We never saw the years after that C/7 were together.
I can understand it.
Chakotay like Janeway was alone and most likely lonely.
Seven filled that void for him and he took for granted that she'd always be there. With her gone, he went back to loneliness which lead to depression thus dying of a broken heart.
Chakotay didn't really have many "friends" on Voyager anymore.
He didn't really get along w/ Tuvok, Tom or Neelix so well.
Be'Lanna hooked up with Tom.
Seska was a spy
He had a fondness of Harry
He was a little distant w/ the Maquis crew.
Janeway was putting him off.
So it seems his whole world became Seven.