Promises are easily made, but not always easily kept. Whether someone keeps their promise could depend on the motivation behind making the promise in the first place, according to a research study published in 2009 in “Neuron.” People usually make promises to gain cooperation or benefits in the future or because they feel making and keeping the promise is the right thing to do. When your best friend breaks a promise, figure out why before determining consequences.

Handle Yourself First

When a promise isn’t kept, especially by your best friend, you probably feel angry at being let down, frustrated if you were counting on the results of the promise, irritated at yourself for believing your friend and sad because trust was broken and the relationship was harmed, according to management coach Vickie Gray. Take a few moments to calm yourself and perform self-care, such as deep breathing, exercising to burn off the adrenaline rush or counting to 100 to reduce the temptation to berate your friend. This will give you the calmness and clarity needed to discuss the problem rationally with your friend.

Get the Story

Give your friend the benefit of the doubt, suggests the Southam Consulting team in “The Ten Secrets to Managing Broken Promises, Violated Expectations, and Bad Behavior.” State the facts as you see them, such as “The paper you promised to help me with is still unfinished," or "You promised you'd come to my dance recital." Give your friend a chance to explain why the promise wasn’t kept. Listen carefully and allow the story to unfold. There could be a logical reason for the broken promise.

Explore the Consequences

Your friend might not understand the consequences of the broken promise, according to health and wellness journalist Michelle Gielan in an article for “Psychology Today.” State your feelings, using "I" language. For example, you could say “I feel like I’m not important to you.” Ask why your friend made the promise initially, so you understand her motivation -- she might have meant it at the time because she wanted you to feel better, but forgot to follow through because your emotions improved. Let your friend know that broken trust makes it difficult to trust in the future. If you will incur a penalty for the broken promise, such as a poor grade on a project or a missed opportunity for benefit, add that to your consequence explanation.

Resolve the Promise

Find out how your friend intends to resolve the issue. Your friend might quickly perform the promise or explain to a teacher that the problem was his responsibility and plead for a reprieve. Explain that you would prefer not to receive promises if they won’t be kept because the breach of trust will damage your relationship.