How we cite our quotes: (Day.Story.Page)
Quote #4
Not long ago, there lived in our city […] a painter called Calandrino, a simple, unconventional sort of fellow, who was nearly always to be found in the company of two other painters, whose names were Bruno and Buffalmacco. These latter were a very jovial pair, but they were also shrewd and perceptive, and they went about with Calandrino because his simple-mindedness and the quaintness of his ways were an endless source of amusement to them. (VIII.3.561)
Here's a relationship based on pleasure and usefulness—Calandrino's a good guy to make fun of alone. Even though these guys spend a ton of time together, they're not friends by any classical definition of the term. It's a superficial relationship.
Quote #5
'[...] since I can find another wife, but not another friend, with the greatest of ease, I prefer, rather than to lose you, not to lose her exactly, but as it were to transfer her. For I shan't lose her by giving her to you, but simply hand her over to my second self, at the same time changing her lot for the better.' (X.8.752, Filomena's tale of Titus and Gisippus)
For the moment, we're going to overlook the whole "woman as a piece of furniture" theme running through here and focus on what's going on between the guys. Boccaccio's playing on the motif of BFFs being mirror images of each other (remember that Titus and Gisippus also look alike) to show that the friends love each other as they love themselves. Sophronia clearly has a problem with this; that's because this version of friendship is a boys-only club.
Quote #6
Men may thus continue to desire throngs of relatives, hordes of brothers, and swarms of children, and as their wealth increases, so they may multiply the number of their servants. But what they will fail to perceive is that every one of these, no matter who he may be, is more apprehensive of the tiniest peril to himself than eager to save his father, brother, or master from a great calamity, whereas between two friends, the position is quite the reverse. (X.8.764, Filomena's tale of Titus and Gisippus)
With this concluding statement to her story, Filomena's just set up male friendship as the ideal for relationships that can exist among people. Perhaps she's doing this as a cautionary tale to the members of the brigata, especially since Boccaccio's already told us that the natural bonds between kinsmen have been perverted by plague-desperation. In other words, you might sell your mother down the river, but would never think of abandoning a friend.