The Absentee — Maria Edgeworth

Just before coming of age, Lord Colambre, the sensitive hero of the novel, finds that his mother Lady Clonbrony's attempts to buy her way into the high society of London are only ridiculed, while his father, Lord Clonbrony, is in serious debt as a result of his wife's lifestyle. Colambre falls in love with his mother's companion, his supposed cousin, Grace Nugent.