People breaking promises to you is a masterclass in why you should keep yours.

Being let down teaches you something instruction cannot: the exact texture of waiting for someone who is not coming. That feeling is the reason reliability matters, and you now know it from the inside rather than as a rule you were handed. Most people learn the value of their own word by first learning what it costs when someone else does not keep theirs.

Use it narrowly. Look at the small commitments you make casually, the texts you mean to send, the times you say you will be somewhere. Keep them or do not make them. Letting disappointment sharpen your standard beats letting it make you suspicious of everyone.