A tradition should be explained before absence is treated as an insult.

Families and groups accumulate customs that feel obvious from the inside and are entirely invisible from outside. Who comes, what is brought, which day is not negotiable, what it means to arrive late. Nobody ever said any of it aloud, and then someone newer misses it and is quietly filed as careless.

If a custom in your circle matters, say what it is and why, especially to people who joined recently. Before you take a missed occasion personally, check whether the person was ever told that it counted.