The director adapted the technique of contrast. Ergo, comparing Authur's smile before he boarded the plane, and the disappointment on the face of his girlfriend, who rushed to the airport just to find out that Authur has left. This is to set a contrast between the two actions, the good and the bad, under two different ethical systems. Which is, Authur leaving the airport in pursuit for a new, and hopefully better love in his life, and his girlfriend rushing to the airport to salvage her relationship with Authur, and step into the halls of marriage with him later on. Judging from an angle with Utilitarianism, i.e. commenting an action only on the results of the action, we can see that because Authur found a new happiness, which brought us a good result, therefore Authur's actions of boarding the plane is ethical, and generally good.