TORCHWOOD, season 3 episode 4 (but honestly that whole season is just continual heartbreak). https://twitter.com/klee_filmreview/status/1264717256275066880

A strong number two is:

Since @liesandarbor brought up another heartbreaking DW one I just want to talk about 11’s goodbye. He travels around to all of his companions and says goodbye. All of these people’s whose lives’ he’s changed. All of these people he’s letting go to live their own life now.

I think the one that hurts me the most is Donna and her family. Because Donna learnt how BRILLIANT she was. And then she forgot all of her adventures.

God I need to rewatch DW and cry...