Because I want to talk about that ending. Wow. I gotta say, in the moment, it really hit me. Thanos accomplished exactly what he wanted, and the final shot suggests he really found his peace in that. But everyone else is left to make sense of what just happened, definitely including the audience.
"The swirly sphere ascends and flies out into space, leaving the ravaged Earth behind, where seven billion people made fully dependent on a highly technological supply chain over the course of several generations have now been plunged into a barbarous, nightmare dark age sure to inaugurate a millennium of murder, brutality, and misery. But... Jaden Smith called Jennifer Connelly "Mom"! So that counts as a happy ending, r-right?"
Tails: All's well that ends well, right?
FTA: THE CITY'S BEEN FUCKING DESTROYED!
HAPPY END!
Come on, pal! Cheer up! We did it! We got Boo home! I mean, sure, we put the factory in the toilet, and... Gee. Hundreds of people will be out of work, now. Not to mention the angry mob that'll come after when there's no more power, but hey! At least we had some laughs, right?
Once, there was an ugly barnacle. He was so ugly that everyone died. (Patrick's facial expression becomes a happy one) The end.
And so, as the sun rises on the Matrix, most of humanity's still enslaved by the robot overlords, while the rest continue to rot in a damp cave with poor ventilation miles underground. What a glorious ending to over six hours of movie!
—Kevin Murphy, RiffTrax commentary of The Matrix Revolutions
Homer: Well, we didn't get any money, but Mr. Burns got what he wanted... Marge, I'm confused. Is this a happy ending or a sad ending?
Marge: It's an ending. That's enough.
When all is said and done, Arisa really hasn't taken any steps towards recovery, and in fact still seems very invested in what can only be called an emotionally unhealthy (or even abusive) relationship. This drastically affects the enjoyability of the series' finale, bringing it into territory that, while sadly not unfamiliar in shoujo manga, had at least been absent previously.
This is actually one of the more depressing things I've sat through, and I've watched Salò and A Serbian Film. This is a movie about a kid whose love for music is transmorphed into something quote-unquote evil by his paranoid parents until he is turned into a raving, bigoted fanatic who loses his friends, his personality, and any sense of independence.
—Brad Jones, reviewing Rock: It's Your Decision. The movie is supposed to be about God guiding a teenager away from sinful music.
O. Henry’s The Gift of the Magi is a tale of another sort of deadweight loss. I’ve always hated it for the cruel joke the author plays on the characters, doubly so since he declares their gifts a model of wisdom rather than heartbreak. How can that outcome be good? Everyone is worse off!
—Virginia Postrel, The Glamour And Peril Of Getting Gifts

WOAH WOAH WOAH! Don't try and pull that "happily ever after" crap! HUMANITY WENT EXTINCT, THE PLANET IS FLOODED, AND THE LAST MEGA MAN IS STUCK IN SPACE FOREVER, BECAUSE LEGENDS 3 IS NEVER GONNA HAPPEN! That peaceful future that Doctor Light fought so hard for turned out to be total bullshit, and if you think about it, it's all his fault! Love and peace are lies, God Is Dead, and we're all totally f***ed!
Jorgen: And then Vicky crushed the barbarian in her claw, destroying him forever!
Binky: Wait! What kind of bedtime story is that? That's not a happy ending!
Jorgen: It is for me.
Binky: Wait! What kind of bedtime story is that? That's not a happy ending!
Jorgen: It is for me.
—The Fairly OddParents!, "Timmy the Barbarian!"
"Kids, we just have to learn to accept this. Like one of those stories on Dateline, where a family member suffers a horrible accident and becomes a burden on everybody. Sure, they pretend to be happy, but they're dead inside. They're dead. And that'll be our lives."
—Lois, Family Guy
Peter: Well, I'm glad everything's back to normal.
Lois: No, it isn't! Meg got the dead janitor's feet, Brian and Stewie got thrown into New Hampshire by the Hulk, and you're a beam of light.
Chris: I have The Shining now.
Lois: And Chris has The Shining now.
—Family Guy, "Girl, Internetted"
Willy Wonka: But Charlie, don't forget what happened to the man who suddenly got everything he ever wanted.
Charlie Bucket: What happened?
Willy Wonka: He lived happily ever after.
Devin J. Stone: Yeah. Such a heartwarming ending. The only problem is that because Charlie has won this as a result of the contest, he's gotta pay taxes on his winnings. So while Charlie may be very happy in the moment, he doesn't realize that he's going to be saddled with a tax bill in the tens if not hundreds of millions of dollars. So, unfortunately, he's probably going to have to liquidate a large portion of the Wonka factory in order to settle up with the IRS. The truth is when you get everything you want, you don't really live happily ever after.
—LegalEagle, Laws Broken: Willy Wonka & the Chocolate Factory
This is what the world needed: a catatonic king, a failure of a Hand, an acolyte posing as an expert, and a cutthroat running the finances.
—Preston Jacobs, Preston's Game of Thrones Season Eight Watch: Season 8 Episode 6 The Iron Throne Review

Owen: Aww, they're best buds now, and everything's gonna be alright!
Courtney: No. They're going to terrorize the entire world.
Owen: Yeah. We did a bad thing.
Courtney: No. They're going to terrorize the entire world.
Owen: Yeah. We did a bad thing.
—Total DramaRama, "Ghoul Spirit"
So ride along for a thrilling adventure that will have audiences' cheering when our hero finally makes it back to Earth alive. Even though we lost the Space Shuttle... and the International Space Station... And the Chinese Space Station... and the Hubble Telescope... and Facebook... and made so much debris that we won't be able to leave the Earth for hundreds of years... Guess we won't be going to Mars anytime soon.
—Honest Trailers in their review of Gravity
Elan: Will this story have a happy ending?
Oracle: Yes-For you, at least.
...And Patrick Wilson and Halle Berry land back on Earth, and everybody lives happily ever after. Well apart from the billions of people killed by fires, floods, earthquakes, asteroid strikes and suffocation from having the atmosphere literally ripped away into space. Not to mention the billions more rendered homeless by massive global destruction of every major city, or the billions more than that that will almost certainly die from starvation and disease due to the world's livestock, viable farmland and critical infrastructure being entirely destroyed. Thus dooming humanity to a new dark age of brutal survival where all semblence of law and order has broken down.
At the end of the game, you find out that the person who ordered a hit on your brother was actually yourself. Apparently, he treated his girlfriend like trash and was overall impossible to tolerate, so your main character decided to end it all. I must admit that I can appreciate a twist like that, but the way all of this is staged is just utterly ridiculous. Why are we hugging to victorious music playing as the sun is going up? I am literally a murderer and I should be ashamed of myself!
—DustinEden on the ending of Need for Speed Carbon: Own the City