Mandibles "Mandy" Carapace hated Queen Chrysalis.
He hated her hare-brained schemes, he hated her commanding and dominating nature, and he especially hated her unending arrogance.
So, when the Canterlot Invasion failed and he was sent careening into Ponyville, he felt no particular rush to return to her.
Author's note: Contains Romance, but there aren't enough tags to include it, so I chose Drama over Romance (because the Drama is the main theme of the story, while the Romance is a side-plot that feeds into said Drama).
And now, I've also added the "Alternate Universe" tag, because of the stuff involving Mothra and Chrysalis.
Sequel is here.