Fun fact: actually, the man is
always supposed to apologise not matter who steps on whose feet during dancing. The man is leading, so it's always his fault. Lady stepped on his feet? He didn't move his feet quick enough.
He stepped on the lady's feet? He moved his feet too quickly.
That's what my dance teacher (who is a man) taught us
So ladies, never apologise for stepping on feet during a dance :'D