Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Mary Poppins
The twins forgetting how to talk to animals as they turn one.
Every time Mary Poppins leaves the Banks family, especially when she leaves the children mementos and reminds them that nothing lasts forever. P.L. Travers claimed that even she cried when Mary Poppins left the Banks children for good in Mary Poppins Opens the Door.
When Jane and Michael ask Mary Poppins in the second and third books how long she will stay, she gives rather vague answers, making her departures unpleasant surprises for the Banks family.
Doubly so when you learn that "Feed The Birds" was Walt Disney's favorite song. He would frequently ask the Sherman Brothers to play it for him after their Friday afternoon strategy sessions. And then? They played it at his funeral. Y'all can go cry now.
And triply so when you learn, years later, that the bird lady was played by Jane Darwell, already no spring chicken when she won the Best Actress Oscar for playing Ma Joad in The Grapes of Wrath a quarter of a century earlier. It was her last film role.
What makes it worse is when Mr. Banks goes past the cathedral as he makes his way to getting fired; a Dark Reprise (or perhaps regular reprise, since it sounded dark anyway) swells as he looks at the utterly empty steps of cathedral, then up into the air.
In fact that cathedral scene is easily the biggest tearjerker in Disney history.
Ultimately, the story of Mr Banks. He's a cold and selfish misogynist looking to be remembered in the world of banking. His life is turned upside down by the introduction of Mary Poppins, who brings fun to his family until he realises what a failure in life he's been. He is ridiculed before his peers, sacked from his job, and then reconciles with his family, intending to spend more time with his children. And he recovers his job at the end!
Near the end, when Bert is describing George Banks's attitude towards his work and family (for emphasis, to a slow melancholy version of "The Life I Lead", where Mr. Banks had described much the same thing near the start of the film):
You're a man of 'igh position, esteemed by your peers And when your little tykes are cryin', you 'aven't time to dry their tears And see them grateful little faces smilin' up at you Because their dad, 'e always knows just what to do. You've got to grind, grind, grind at that grindstone Though childhood slips like sand through a sieve And all to soon they're up and grown And then they've flown And it's too late for you to give.
Mr. Banks opens the song with an equally sad statement to the position he's found himself in. The whole song, A Man Has Dreams, is pretty depressing.
A man has dreams of walking with giants. To carve his niche in the edifice of time. Before the mortar of his zeal has a chance to congeal The cup is snatched from his lips. His flame is snuff ab'rning. He's brought to rag and ruin in his prime.
When Mary Poppins watches Jane and Michael go off with their parents without a backwards glance. Just because something is right and correct doesn't automatically make it less sad.
However, in Mary Poppins' view: "Practically perfect people never permit sentiment to muddle their thinking."
Oh, balderdash. Her umbrella didn't buy that line, and neither should anyone else.
When Michael and Jane run away from the bank and run into Bert who comforts them and he tells them their father loves him, and they say that he doesn't love them at all. Bert explains their father to them, and how no one is there for him, at the end of the day, and how Bert feels sorry for Mr Banks having a dead end job
Michael: Father? in a cage
When Michael apologizes for inadvertently causing the bank riot, and gives his father the tuppence, hoping it'll make everything better. Awwwwww
Mary's departure and the moment when she says goodbye to Bert and kisses him on the cheek.