Aida/Tear Jerker

- Aida and Amneris's Dark Reprise of "My Strongest Suit":

Aida: So a life of great potential is dismissed, inconsequential?
Amneris: But I'm only ever seen as being "cute". So I'll flutter to deceive-
Aida: No, you must believe that one day you're bound to find
Both: A stronger suit.

Mereb's Dark Reprise of "How I Know You".

Mereb: There is time, there is a place when love should conquer all. The rest of life is pushed aside as truth and reason fall. But, only if that selfishness can lead to something good. I thought I knew you, Princess, but I never understood. I don't know you...I don't know you..."

"Written in the Stars"
- And the song immediately after that, "I Know the Truth". After the lovers have departed, Amneris walks out, revealing that she's heard everything and finally facing the fact that her upcoming marriage is a sham--"it's over, it never began"--all the while still getting ready for her wedding. She doesn't even need to tell us how devastated she is by all of this, it's evident in her stunned expression and her body language. It's an utterly heart-breaking moment for someone who hasn't really done anything wrong except be oblivious to the fact that Radames doesn't love her.
And even more so, "Enchantment Passing Through (Reprise)", as the lovers are slowly deprived of light and air, embracing one last time before the tomb is sealed for good.
Amneris' speech to her father as he sentences the two lovers to death for treason. Amneris knows he is dying from Zoser's poison, and if he kills the two she will be completely and utterly alone. She exercises her role as future Pharaoh and allows the lovers to die together, an act of mercy for two people she has come to love..
Watching my high school production, I was cut up to see Mereb die.