This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Denji Sentai Megaranger
Episode 16, when the Megarangers learn that they are going to die thanks to Poison Moth Nejilar. Shun can't become graphic designer like he wanted, Kenta won't be able to play games with his younger friend anymore but the saddest is that Miku won't be able to become a bride *sniff* They get better
Episode 35. When Kenta and Miku thought Yusaku was going to die he doesn't.
Episode 49. Hinelar succeeds in exposing the Megaranger's true identities, causing them to be expelled. All of them lose the will to fight the Nejirejia anymore.