Before everything else they have been through. The Dazzlings and John Sweetstuff had a very...unusual start to their relationship. One of those was having terrible voices after their powers where taken away, but singing wasn't the only thing The Rainbooms stole from breaking them, and while an Equestrian ritual may have given back what they lost, sometimes it takes practice to earn back what you truly desire.

EDIT: deleted the prologue found it needless and detracting to the story as a whole