Come, Proteus; 'tis your penance but to hear The story of your loves discovered: That done, our day of marriage shall be yours; One feast, one house, one mutual happiness. (5.4.14)
In the end, Proteus falls back in love with Julia (who takes him back) and Valentine and Silvia are engaged with the Duke's blessing. (This is typical of Shakespearean comedy. At the end of his comedies, Shakespeare always marries someone off, which you can read more about by going to "Genre.") Here, Valentine tells Proteus they should all celebrate by having a double wedding. Does this mean that Valentine's bromance with Proteus is being replaced by his marriage to Silvia? Not necessarily. Valentine says the double wedding will be "one feast, one house, one mutual happiness." "One mutual happiness"? Is Valentine talking about the mutual happiness between husband and wife? Or is he talking about the mutual happiness between him and Proteus?