From the source:
 
THAT’S MY WOLF YOU’RE FUCKING WITH SPARKLE!!” Spitfire roared as she jerked Twilight off the shelf and quickly slammed her back against it. “DO YOU HEAR ME?! MY WOLF!!” Spitfire shifted her grip so both of her hooves were under the joints of Twilight’s forelegs and she hoisted the unicorn high, so now the purple unicorn’s hind legs dangled freely in the air. Twilight now had utter terror in her eyes as tears streamed down her face. Spitfire’s nostrils flared as she breathed hot, rage filled breaths against Twilight’s chest as she looked up at her. “And he’s worth ten of you!” She seethed through clenched teeth.

Spitfire: How dare you take Rainbow Dash away from me!

Wow, these make so little sense.
 
The wolf goes crazy and tries to kill Fleetfoot in the below image.
 
>>484856
 
Yet Spitfire ‘loves’ it enough to stand up for it in the face of an alicorn whom was an Element of Harmony?
 
Geeze, who swapped Spitfire for a xenophile changeling?