The phrase 'with ill grace' is used to describe someone's behavior when they are doing something unwillingly or reluctantly. There are a host of synonyms that can be used to express similar sentiments, such as grudgingly, sullenly, reluctantly, unenthusiastically, sourly, morosely, and begrudgingly. These words describe an attitude of disapproval or unwillingness that is often accompanied by a frown or a scowl. When someone is behaving with ill grace, they may also act in a surly or peevish manner, expressing their displeasure with their body language or tone of voice. It is important to choose the right words to capture the nuances of the behavior being described.