The very end of the first season when Toori does rescue Horizon, and the two end up in a hug.
Horizon and Toori's date in the second season, where he talks to her about retrieving her emotions and convinces her to follow Musashi in their mission to recover the Deadly Sin Armaments.
After Malga gets slapped out of her emotional rant, she asks Margot if she thinks they are equals. Margot tells her that Zwei Frauen means "to stand side-by-side", and that they have that nickname because that's what they always try for.
Tenzou's confession to Mary. From his statement of Musashi's mission to save those condemned to an unjust death by the Testament, to him shooting down Mary's reasons why she can't be with him, and finally the moment when he removes his scarf to share a kiss with her and replaces it with the one she made for him, it's one of the most incredibly romantic and heart-melting sequences ever.
Muneshige and Gin reuniting on the Musashi in the final episode of S2 kicks off this D'aww inducing exchange:
Muneshige: Would you stay forever with a man whose inherited name as Muneshige Tachibana has been lifted?
Gin: What about you, Lord Muneshige? Do you want to be with an unsociable woman who is not the wife of Muneshige Tachibana?