To elaborate: Jeremy is killed, permanently this time. His ring won't bring him back again, since as a Hunter he counted as a supernatural creature. Elena is in denial for the whole episode, waiting and waiting for the one hope she has, that Bonnie will find a way to bring him back. And when that fails, Elena snaps as it dawns on her that her little brother - the only family she has left in the world - is gone for good. She asks Damon to take his body downstairs, so that she can douse it - and the whole house - in lighter fuel so she can burn everything down.
Elena: What else are we supposed to do with the body, Caroline?! I-I mean (blinks back tears), there's no room in the Gilbert family PLOT! (throws pictures to the ground, they shatter) Jenna and John took the last spots! (lights the match)
Stefan: No, no...Elena, stop...
Elena: There's nothing here for me anymore, Stefan! Every inch of this house is filled with memories of the people that I love that have died. (sobbing) My mom, my dad, Jeremy, and Jenna, and Alaric...John, even John! I mean, they're all dead! Everyone is dead! (matchstick burns perilously low, she ignores it) S-So how am I supposed to...I-I can't, I can't even, th-there's nothing left for me-Aaah! (drops matchstick, Damon catches and extinguishes it)
Damon: Elena...I need you to calm down...
Elena: NO! No, I can't...(drops to her knees and wails) Ican'tIcan'tIcan't...I can't! (openly sobbing) No...it hurts, it hurts....just make it stop...please make it stop, it hurts...(continues to cry)
- And then Damon makes her turn off her humanity before she has a complete breakdown. Yet, she still burns the house down anyway, because 'it's the best cover story' and she doesn't want to come to this house anymore. Her grief and sorrow is still that complete, even with her emotions gone.
- Matt's reaction when he sees Jeremy's body. He tries to help Elena see through her denial, and has to be strong for everyone else. It's only when he's alone that he falls to pieces.
- Not to mention, Caroline's constant calls to Tyler knowing that he won't answer her back. She seems to be less sane with each one.