I understand, my husband has expressly told me he doesn't want to celebrate 'landmark' birthdays and we respect that - a persons birthday should be about what they want not other people want IMO.

You write you feel resentment a lot. Have you been able to explore why you feel that? Resentment can be felt when we feel we do what others want rather than what is right for us and we don't feel we are able to safely express our feelings about that. I have experienced resentment before and it is a very inwardly toxic feeling, it wasn't easy for me to learn to express my feelings healthily, it still can be a struggle sometimes, I was brought up to 'be good' and 'behave nicely' if that rings any bells.