If every bar was full and the client still turned the dress down, you almost certainly went over a max limit. Some requirements say max next to the number: you have to stay at or under it, not fill it. Rose's warm work dress, for example, allows at most Cute 25 and Romantic 20. Go over either and the commission fails, however full the other bars are.

How to avoid it

Read every requirement before drafting

Look for "max" beside the number. Max 10 means 10 or less; 0 is fine.

Watch the red and gold bars

Hover a pattern, fabric or accessory: gold raises a requirement, red lowers it. A "cute" sleeve can push you over a cute max.

Check again after fabric and accessories

Fabric moves the numbers a lot. A dress that was under the max in the sketchbook can end up over it.

Already rejected?

You can't redo the commission, and you don't get the payment. You can win back the friendship you lost later by giving that character a dress.

Related

Sources: Steam discussion: Filled bars but got rejected anyway?, Guidexon beginner's guide.