Poor Pounded Puppy
This file written by u/KardinalSin is the sequel to "I made your girlfriend my bitch, You're next". You can find the first part linked, where I bring out your girlfriend, decked out like a puppy, and force her to suck your cock.
Now, a few days have passed since you psycho ex-girlfriend captured you and revealed to you the harsh tutelage she has used to transform your adoring girlfriend into a perfectly submissive little puppy girl. After making you watch for days as she's continued her training, she has a new game she wants to play with you and your girlfriend... the most extreme test of her training yet, something which will leave both you and her panting.