Familiarity should not become permission to disrespect you.

Long relationships accumulate informality, and informality can slowly turn into a lower standard of treatment. The tone that would never have appeared early on becomes ordinary, and both people stop noticing because it happened gradually. Comfort is meant to make things easier, not to remove the basic courtesy you would extend to a stranger. Familiarity is not a licence.

If you would be surprised to hear a new acquaintance speak to you that way, that is a useful test. Raise it as a specific instance rather than a general accusation. Long relationships can absorb this kind of correction more easily than people expect.