"Take the demon spawn away from me. Oh, please Dash please!" "It isn't a demon spawn for the hundredth time, and you know bunnies aren't my thing..." "Please Rainbow...don't make me go through It's torment....I've gone through enough." "Ugh fine Fluttershy! If it'll make you stop with the cryin'." "I am ever so grateful. I'll be sure to bring flowers to your funeral."
I think, he's kind of guy (i presume, Angel's male), who thinks that only he himself could be harsh with FlutterShy. He bullies her around like spoiled brat (or maby even like evil-husband). Very likely that FS herself spoiled him. But when somepony other offends his "mommy" ("darling"), he becomes defensive.