Sebastian's line during Ariel's first night at Prince Eric's place:
Sebastian: You are hopeless, child. You know that? Completely hopeless.
The wedding scene at the end, where everyone's happy and Ariel is saying goodbye to her dad.
Ariel: I love you, Daddy.
The moment where Eric bows to Triton and he nods back to him in approval.
And when Eric takes off in a rowboat with a harpoon to rescue Ariel from Ursula, starting off his Moment Of Awesome:
Eric: I lost her once, I'm NOT going to lose her again!
Later on in the scene:
Ariel: Eric, you've got to get away from here!
Eric: No, I won't leave you!
Grimsby advising Eric on his feelings for Ariel. He may be a Stiff Upper Lip, but he turns to the prince and gives him wonderfully heartwarming advice on love. And it would have worked too, if not for Ursula's magic.
Grimsby: If I may say so Eric, far better than any dream girl, is one warm, and caring... and right before your eyes.
Triton's realization about Ariel's feelings.
Triton: She really does love him, doesn't she, Sebastian?