Tim Madigan in Philosophy Now:
In Book VIII of his Nichomachean Ethics, Aristotle categorizes three different types of friendship: friendships of utility, friendships of pleasure, and friendships of the good. Friendships of utility are those where people are on cordial terms primarily because each person benefits from the other in some way. Business partnerships, relationships among co-workers, and classmate connections are examples. Friendships of pleasure are those where individuals seek out each other’s company because of the joy it brings. Passionate love affairs, people associating with each other due to belonging to the same hobby organization, and fishing buddies fall into this category. Most important of all are friendships of the good. These are friendships based upon mutual respect, admiration for each other’s virtues, and a strong desire to aid and assist the other person because one recognizes their essential goodness.
The first two types of friendship are relatively fragile. When the purpose for which the relationship is formed somehow changes, then these friendships tend to end. For instance, if the business partnership is dissolved, or if you take another job, or graduate from school, it is more than likely that no ties will be maintained with the former friend of utility. Likewise, once the love affair cools, or you take up a new hobby or give up fishing, the friends of pleasure will go their own ways.