Some times it’s good manners but sometimes it is an expectation of good manners. Chivalrous behaviour might include always paying for a dinner if you’re a man, good manners (on the woman’s part) might be paying half, or indeed paying all of it if they earn more. Much of what is chivalry does fit into politeness and manners but not all of it.

You can’t have chivalry and equality. They are incompatible. You can have manners and politeness between the sexes and equality. You can even have two people who agree this inequality is one they enjoy because it fulfils an aspect of their psychological set up - but that isn’t the same thing.

That’s why the debates are so complicated. Many feminists say they’re happy to pay. Or pay half. Many women enjoy chivalry, and many men do too but it’s complicated because at its heart it is politeness generated by sexism. Men are rarely chivalric to each other….. sometimes, but not usually.