This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Cinderella III: A Twist in Time
Lady Tremaine goes out of her way to torment Cinderella one last time before she and her daughters leave for the palace by taking her last glass slipper, breaking it, and telling her to clean it up before she leaves.
Prudence leads Cinderella away from the Prince and orders her to clean a dusty room, essentially leaving Cinderella back where she started.
Anastasia's whole character arc is heartbreaking because she's getting all this love and attention—possibly the only real love and affection she's ever had—for something she didn't do.
Anatasia's protest "But I want someone to love me for me!" when she ruins her wedding to the Prince. Would she have been so desperate to catch a boy's eye if her own mother had truly loved her?
Hell, her Heel Realization begins when Cinderella asks her if being the Prince would really make her happy, and if she even loves him. She realizes that no, this won't make her happy - and her mother doesn't care.