Regarding the discussion here on happy endings versus tragic ones, it all depends; I mean, there's no hard-and-fast general rule that you should almost never use one or the other, since it all depends on what works best for the individual movie in question. I do get any bias people might have against happy endings on principle, since Hollywood shoved those down our throat all the time back in its Classical era, but that's more of a problem with the endings feeling forced, like the abrupt upbeatness at the end of the studio cut of The Magnificent Ambersons; it's just as possible to force a dark ending, even if it "fits" the general tone of its movie, like the pointless, nihilistic conclusion of It Comes At Night.
And on the flip side of that, sometimes endings work because they clash tonally with the rest of the movie in question, like the way that Ripley's moment of peaceful slumber at the end of Alien feels like the most well-earned happy ending ever, after such a bleak, disturbing experience (which I think works better than the original proposed ending of the Xenomorph killing her), or vice versa, like the way that Futurama's "Jurassic Bark" is a typically hilarious episode of that show, only to end up with one of the biggest emotional gutpunches in TV history. It all just depends, you know?
And on the flip side of that, sometimes endings work because they clash tonally with the rest of the movie in question, like the way that Ripley's moment of peaceful slumber at the end of Alien feels like the most well-earned happy ending ever, after such a bleak, disturbing experience (which I think works better than the original proposed ending of the Xenomorph killing her), or vice versa, like the way that Futurama's "Jurassic Bark" is a typically hilarious episode of that show, only to end up with one of the biggest emotional gutpunches in TV history. It all just depends, you know?