The opening of the movie itself is one, as it shows despite all the tricks and backstabbing, Lupin and Fujiko truly do love each other as much as people like them are capable.
The episode "Goemon's Close Call" from the second anime series, especially the end, where Lupin and Jigen manage to rescue Goemon from the hands of two assassins, who have spent the episode torturing him in an attempt to get him to tell them Lupin's weakness. Lupin cradling an injured Goemon with a look of absolute fury on his face in particular just shows how far along these two characters have come since the days they were sworn enemies.
The end of the manga story "The Holmes's Violin", where Lupin burns the magical violin he worked so hard to assemble just so that Pinocchio can finally end his existance. Yes, thatPinocchio.
When Lupin found himself cursed by Tutankhamen's mask, it fell to Fujiko to shoot him should he lose control before the others found a way to put the mask back and break the curse. She did not take to this role with any amount of zeal, and planned to use a second bullet on herself immediately afterwards, if it came down to it. Bit of a Tear Jerker as well, but it's further proof of how much she loves the dork.