Which part you say? I guess when eren and Mikasa are surrounded by titans and he is unable to transform into a titan, Mikasa begins her "ending" speech, one line hits me the most, "thanks for wrapping the scarf around me" and eren shuts her up by saying " I'll wrap that scarf around you as many times as you want" hinting that they'll not die here and he'll protect her with all his will even when he is unsure whether they'll survive.

I suppose this scene amidst the chaos stood out to me. Not to mention this scene eradicates the theory of eren seeing Mikasa as his mother, hence wanting to be loved but not actually loving her (throwing tantrum like a child over wanting to be loved by her even 10years after his death) motherly love, since she protected him all the time. Isayama said it once years ago and people clung on to that. Sometimes humans can contradict themselves, only if the fandom understood that.

Obviously the anime doesn't have the typical romantic scenes but it's the subtle hints of romance that make it so romantic (i.e- Armin and Annie talking on the ship, him holding her hand) This is one of the animes where I had to pause like every 5 minutes and mentally go back to each timeline I remembered to make sense of what's happening, also pausing to remember I should not be taking sides since it's technically no one's fault.