The US Vogue editor has only worn two styles of shoes for over 10 years - both made by Manolo - and he admitted if she were to turn to one of his rivals for her footwear now he would be displeased.
He said: "I am incredibly thankful for Anna's loyalty and if she chooses to move in another direction, I would also respect that. Betrayed is too strong a word but I'd definitely be hurt."
The Spanish designer thinks Anna has refused to deviate from the two styles - which have been nicknamed AW - because she is so sure of what suits her.
He explained to fashionweekdaily.com: "Anna knows herself very well and what suits her best. Anna always like to have her shoes, like everything in her wardrobe, impeccable at all times. Her favourite colours are skin tones. I have produced two skin tones that particularly suit Anna."
Choosing Anna's shoes is a collaborative process for the designer and the editor and says it changes depending on her wardrobe.
He explained: "I often talk to Anna about what's inspiring her that particular season and what she's ordered for her wardrobe. Anna has fantastic legs, and her feet are always meticulously groomed. We're always discussing materials and adjusting the heel heights and whether or not straps should be wider or stay the same. In the end, it is always up to Anna."