You can hurt someone without knowing it. You’re still the one who gets to fix it once you do.

Intent and impact come apart all the time. You can be entirely well-meaning and still land badly, because the other person’s history and the situation and the timing are all doing work you cannot see. Not knowing is genuinely not your fault. What happens after you find out is a separate question, and that one is yours.

If someone tells you that something you did hurt them, resist the urge to explain what you meant. Start with the effect, apologize for that, and ask what would help. Your reasons can come later, if they are still relevant, which they usually turn out not to be.