An unspoken preference cannot become a fair accusation afterward.

A rule nobody was told cannot be broken, only stumbled into. It is common to hold a quiet preference, watch someone do it differently, and feel genuinely wronged, since the expectation was vivid to you the whole time. But from their side there was nothing to follow, and the complaint arrives as a surprise test they have already failed.

Before an event, a shared task or a visit, say the one thing that matters most to you, even if it seems petty out loud. Petty and stated beats reasonable and hidden. If you are building a case after the fact, ask whether the other person was ever told.