What a let down. So it all come down to humpty dumpty feeling salty and took it to the world because he thought he got dumped by his idol#-.-). I thought he willingly stay behind after reading ellie's letter but nope it's all misunderstanding (︶︿︶)=凸 I expect more with him being ikemen too, so wolfram sit still the throne still yours.
No it is just the straw that breaks the camel's back.
He was already mightily suffering and saw his idol as the only oasis. Then the perceived betrayal broke him completely because now he really lost someone he thought he could trust. The White Bones component helped solidify the betrayal in his mind too. For a broken person like Humpty Dumpty only a full undivided affection could appease him. He wanted more than what Ellie was willing to give him, which he saw as a betrayal. So the fact that White Bones (who is a vampire, which solidifies in his mind that Vampires are 100% robbers of his happiness, from life, body autonomy and even love) is number 1 for Ellie, and that Ellie only wrote him a letter instead of physically carrying him away, broke his trust in Ellie.
I see this flashback to Ellie in his pure state (Humpty Dumpty had seen Ellie in his bad sickness ridden state) as him revisiting that pivotal point/catalyst of his evil-doing, and his denial that he had done so much wrong to Ellie (he did not want to remembee the disease ridden uglified Ellie). Why I said denial, because if he was circumspect he would see Ellie in the last form before his death, and see Eric for who he is. But he chose to see Ellie in that form where he was still Humpty's white knight.
I take that scene as Humpty Dumpty still wanted to be saved/still searching for a savior, but otherwise is unrepentant in what he did.
If Humpty Dumpty regrets what he did to Ellie then the portrayal will be different. There's this trope where redemption is portrayed as first seeing the slighted party (in this case Ellie) in their final form, before morphing to their younger/past form to signify forgiveness.
However, I would argue that all of this conjencture is ultimately futile since the story is still to be continued. My advise is to just sit back, relax, and enjoy that damn fine face.
One shouldn’t ask for break up butt naked lol(づ ̄ ³ ̄)づ