Emma To Hakushaku

Emilia, the only daughter of a wealthy commoner, falls in love with the charismatic aristocratic Dominique. The homely Emilia, understanding the purpose of property, rejects his advances. A stoke of misfortune then forces her to withdrawal from society and change her name to Emma. No longer a woman of means, Emma becomes a governess for the Earl of Chard's progeny (should be Somerset or Northumbria but w/e)...
You have three guess as to whom was to inherit that title, and the first two don't count.