So he was not technically invited, but still attended. He hates dancing, and yet he dances. This sounds like a man driven by a sense of responsibility, or something of the like.
His worry about being attacked while dancing has a double meaning. It could easily be as simple as a person commenting that he is not an exceptional dancer, though he appears to be.
And who might be tapping his shoulder? The Earl’s son, with new-found determination toward dancing with the young lady? Or an undisclosed attacker?
Some typos: you’ve got an extra period after the first question mark, and “sings” should be “signs.”