Willoughby is one serious player. He's a major pick-up artist, and he seems to leave a trail of broken hearts wherever he goes. At the end of the book, he comes right out and admits this to Elinor – before he met Marianne, he'd been a love 'em and leave 'em guy, who didn't feel bad about abandoning his lady friends in desperate situations (like poor Eliza, the Colonel's ward). He's a real Casanova, and his charm works immediately on impressionable, romantic girls like Marianne. Even sensible Elinor is taken in by him for a while, which is really saying a lot. On the outside, he's everything Marianne dreams of – handsome, poetry-loving, musical, and supposedly rich. On the inside, though, he's riddled with problems, like debt, unfaithfulness, and general debauchery. Who even knows what Willoughby gets up to when we're not watching him?
However, change and development are the watchwords of this text, and even this inveterate playboy is transformed over the course of the novel. He goes from thinking that Marianne is just another toy to play with and discard, to having his own heart broken by the impossibility of being with her. He seems to settle down after this episode; even though he doesn't love his wife the way he could have loved Marianne, he manages to get by. Marianne continues to be his ideal woman, even as the years go by – his experience with her clearly changed him for life in some ways.