Changelings in my mind are pretty much just Locusts, feeding off another races love and moving on, Queen Chrysalis even mentions the fact that "Equestria has more love than any place I've encountered" so the Ponies weren't the first, anyway, have this.
Looks like she suck the life out of it like a vampire. If she produce her own, at least she'll be happy when there's a boyfriend to accompany her, or lust, which is more potent than love.