Kinda OT but with the return of Destiny and comparisons to Becky, I think it's worth discussing.
I don't believe Amber loves or has ever loved Destiny. I believe she loved what Destiny represented. With Destiny, Amber had her first taste of independence and adulthood. She had to listen to authority (Krystle's parents, Kasey's mom, her grandma, her foster parents, etc) all her life which all prevented her from binging to her heart's content. With Destiny, she was alone. She could do whatever she wanted. She didn't have to hide anymore and totally was able to indulge in her vices. Destiny didn't stop her because this was Destiny's first relationship away from home, too. But they managed to hold each other somewhat in check since Destiny refused to quit her job and Amber joined her in order to keep an eye on her. Destiny's era was full of hope, exploration, and growth.
But then Amber became a total bitch towards Destiny and Destiny left. If she truly loved her, Amber wouldn't have treated her so poorly.
The Becky era is more representative of defeat. She settled. Becky settled. They both know that they don't like each other but they doubt that they'd find better. There's nothing going on. Every day it's the same routine, but with that routine comes comfort and predictability Amber doesn't like that. She wants those same experiences that Destiny's era came with, but doesn't want to do any of the work that came along with it. If Amber left Becky and Destiny took her back, Amber would still be just as miserable as she is now because she wouldn't be willing to change any of the other aspects of her life that were different in that era.
TL;DR: Amber never loved Destiny or Becky bc narcs only ever love themselves.