I'm right there with you. I made my sister a table runner with matching coasters. I made sure every seam matched perfectly.
I couldn't have made it any more perfect. My whole family was at her house for Christmas. I heard that she didn't even hold it up to show anyone. Really disappointing. I agree with you, I won't be making anything for her again. On the flip side, I made a large lap quilt for my best friend and she just loved it.
At least we know we did our best, just move on to your next project, and chaulk it up to a learning experience.
Wishing you a wonderful New Year :-D