This is based on opinion. Please don't list it on a work's trope example list.
Tearjerker / Annie on My Mind
Pretty much everything. All the Gayngst, Liza's mother and father's reaction to their daughter's sexuality, the reaction of the other kids at Fosters, pretty much everything after they're discovered.
The reactions of pretty much everyone who isn't supportive. Ms. Baxter and Mrs. Poindexter, the latter especially, are fixed on "fixing" Liza for the sake of their beloved school. Liza's mother thinks it's just a phase. Liza's father pities her for never being able to lead a "normal", heterosexual life. For anyone who has ever experienced this themselves, this is a major, major tear jerker.