Friendship is a necessary part of the good life. Only the last type is genuine friendship. Friendships based on usefulness and pleasure tend not to be very enduring, since they only last as the long as each party derives the usefulness or pleasure he desires from the relationship. Friendship based on virtue is based on wishing the good for the other person. This genuine friendship is necessary for self-knowledge and helps both of the friends to grow in virtue.
Friendship presupposes justice and goes beyond it.
The virtue of a friend is to love. The relationship one has with a friend is like the harmonious relationship between the different parts of the soul of a virtuous man. In spite of what many philosophers may say, pleasure is a good. It perfects actions. The goodness of pleasure is determined by the goodness of the action which it accompanies.