Megumi used being a trial lover as an excuse to try and get closer to Hiroki, she really likes him, but he is not paying attention to her as the opposite sex and as he's the owners son, she doesn't know how to approach him. How will the new part timer work out?

まずは人の気持ちを知る所から…

役不足って、その人にとって役割が足りてないって意味だったと思うけど。
めぐみさんはお試しの恋人じゃ役割が足りてないと暗に主人公にアピールしてるのか？