What happens during the meeting of Orlando and Oliver in the forest in As You Like It?

In act 5, scene 2, the brothers Orlando and Oliver meet in the forest. The scene begins with Orlando responding to something that his brother has just told him. We soon understand that Oliver has told Orlando that he has fallen in love with Aliena, who is really, of course, Celia in disguise. Oliver only met Aliena that afternoon, but he has decided to give to Orlando their father's "house and all the revenue" so that he can live a simple life as a shepherd with Aliena. Oliver says that he wants to marry Aliena and asks his brother to give him his consent.
Orlando is at first surprised that his brother has fallen in love so suddenly. His response is full of questions, such as, "Is't possible that on so little acquaintance you should like her?" and "And will you persever to enjoy her?" However, Orlando, after his initial surprise, accepts that his brother is in love and suggests that he and Aliena should get married the very next day. Although he's happy for his brother, Orlando admits that he feels a bit lonely without Rosalind.