Trust and honesty are a couple of the most basic, and most important, foundational issues in a marriage. Unfortunately, many guys manage to mess these up – often without even being aware they are doing it.
If you don’t do what you say, she will rightly lose trust in you. You cannot avoid this by playing word games to not promise while sounding like you are, or to try and argue that you did not really promise, or by saying that something valid came up and pre-empted what you had said you would do.
Along the some lines, honesty is not something that comes in shades. She does not care that something is technically not a lie. She does not see a great difference between not telling her something and intentionally hiding something. Failing to share anything significant that happens to you is an honesty issue in her mind.
Once you have violated her trust, or shown yourself to be dishonest, it’s a long hard road back. Some men feel it’s not worth the effort, and some get defensive, saying that what they did was minor and that she is over reacting. This is one case where a good offense is a terrible defence – if you have blown it, own up to it.