What is your goal? Relationship or quilt? I think you've indicated you're struggling with talking with them because you want to maintain the relationship. So approach it in a way to build the relationship. Such as:
"I really enjoyed your having interest in my favorite hobby and I enjoyed working with you. What did you like about the process? (open ended sentence), response. I like ___________ about your quilt because__________. What do you like. (response) So you like _______________, is that right? (response) What was difficult or confussing about making this quilt? (response) (repeat her response, ask clarification) What do you think would help this difficulty you've encountered? (If she never asks you for advise, ask permission to give advise, if she say's no [probably not] then let it go." End with "I enjoyed working with so much, I hope we can do it again,(pause) would that be good for you?"