Promises are sacred. Promises are when you commit to another person to complete a task.
People make promises for many reasons. Some to gain trust, to impress, or to give assurance. Or maybe the person finds it difficult to say "no" when asked to make a promise.
Once you break a promise, you break the hearts of the people who rely on you to complete the task. They realise that they are not important to you, which makes them feel small.
For example, a friend promised to help with an important task but didn't show up. Or a married couple promises to love each other forever, only to be unfaithful later.
When promises are broken, people feel betrayed. In the future, people will always doubt you and will no longer trust you. Your relationship will be strained or broken, and it'll be hard to fix.
Yet, you cannot live through life without making promises because some people expect them. And so, make fewer promises. It is easier to keep them. If possible, don't make promises, but deliver on what's expected anyway. People will appreciate you more.