This is how Tahu loses hope goes in The Return of Harmony Part 2.
[The Toa try to use the Elements of Harmony]
[The Lord of Skull Spiders appear]
Lord of Skull Spiders: Bravo, Toa, bravo! [giggles] Harmony in Equestria is officially dead. The Lord of Skull Spiders rules, Celestia drools. [laughter]
[The Lord of Skull Spiders vanishes]
Lewa: It's your fault it didn't work.
Tahu: Who are you talking to?
Lewa: Any of you! ALL OF YOU! I'm outta here! [runs off]
Onua: I better go, too. I've got new better friends waiting for me at the cave. [digs underground]
Kopaka: Yeah! I'm sick of you losers.
Tahu: FINE! Leave! See if I care! I don't need you guys either! With friends like you, who needs...enemies...?
[Tahu's colors fade]
[He sheds a tear which splatters in the shape of a broken heart]
[Tahu walks through Ponyville as the Lord of Skull Spiders' chaos grows. The Lord of Skull Spiders appears]
Lord of Skull Spiders: [laughing] Oh, my stomach! Tahu, you've got to see what I just did.
[The Lord of Skull Spiders shows Tahu his paint]
Lord of Skull Spiders: It's priceless! [laughing]
[The Lord of Skull Spiders sees Tahu is upset]
Lord of Skull Spiders: Come now, Tahu. You've got to get into the spirit of things! [licks ice cream] After all, this is your new home.
[Tahu looks around]
[Tahu looks down hopelessly]
Tahu: Not anymore...
[He moves on]
Lord of Skull Spiders: YES! [triumphant laughter]
[At Tahu's volcano]
Tahu: Pack your things, Ekimu, we're leaving.
Tahu: Don't ask where we're going, 'cause I don't know yet. Just not here.
[He puts away the Element of Magic]
Ekimu: Can't...move. The princess...has been sending these...since I came back upstairs. [belch] Make it stop!
Tahu: These are all the letters I've written to the princess since I've lived in Ponyville with Optimus and Twilight and the others. But why would she send them back?
Ekimu: [groan] [belch]
Tahu: "Real friends don't care what your cover is."
"Friendship is a wondrous and powerful thing."
"And like the path cut through the orchard, there will always be a way through."
"The best thing to do is stay true to yourself."
"Everyone has a special magical connection with his or her friends. Maybe even before he or she's met them."
[As Tahu is reading, his colors return]
[Images of past events flow in his mind]
Tahu: That's it! Ekimu, it's all so clear! Can't you see? The Lord of Skull Spiders is trying to distract us from what's important. He knows how powerful our friendships are, and he's trying to keep us from seeing it. Do you remember what I said the first day we arrived in Ponyville with Optimus and Twilight? I told you that the future of Equestria didn't rest on us making friends. But the opposite is true! The friendships I've made since I've been here are what saved Equestria from peril. And now they need to save it from the Lord of Skull Spiders!
Tahu: You're right, Ekimu. I've got to fight for my friendships. For them. For me. For Equestria!
Tahu: Oh...uh...why don't you just stay here and rest? I'll take care of the whole fighting for friendship thing myself.
[He runs off]
Ekimu: [moaning] [belch]