its actually very simple. zeleena simply snatched the dagger once it was done stabbing pan and rumple.
she then said “i summon thee dark one from whatever realm thou art in.”
She then proceeded to practically wipe everyone’s memory of Rumple thus why we dont see David or Snow or Regina mourning him
we don’t see anyone mourning him because they are not mourning him. they have much more important things to do… save Repunzel, fight their way into the castle (regina’s) worry about their baby, and hide from monkeys… Rumplestiltskin is dead to them, so what can they do for him anymore? nothing. so they forget him
(ok I’ll be a bit mean here to snowing… what can HE do for them anymore? so they forgot him
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