I believe if she knew she made you feel bad she would feel terrible. She probably trusted you enough to let you know what more she wanted in the quilt and didn't think for a second it would upset you. Personally I think she should have just put a dust ruffle on the bed. She probably has no idea how much time and thought (and love) went into this quilt.
I made a quilt for my DMIL and she kept it in the closet. I wasn't hurt just wish I had made something she liked. After she passed away my DSIL wanted it and DH was fine with it so now it is being loved.