Greek philosophers have traditionally distinguished 3 notions that can properly called love: agape, eros, and philia. Agape is a kind of love that does not respond to the antecedent value of its object but instead is thought to create value in the beloved. Like the love that God shows on us, and that we show for God and humankind in general. By contrast, eros and philia are responsive to the merits of their objects, i.e. to the beloved’s properties like his goodness or beauty. While eros is a kind of passionate desire for an object, typically sexual in nature, philia is a kind of affectionate regard or friendly feeling towards friends, family members and even business associates.

For this reason love and friendship often gets mixed up, despite them having significant differences between them. Love is an evaluative attitude directed at particular persons as such, an attitude which we might take towards someone whether or not that love is reciprocated and whether or not we have an established relationship with him/her. Whereas friendship, is essentially a kind of relationship grounded in a particular kind of special concern each has for the other as the person she/he is.

Aristotle posited 3 kind of friendships: friendships of pleasure, of utility, and of virtue. Although it is a bit unclear how to understand these distinctions, the basic idea seems to be that pleasure, utility, and virtue are the reasons we have in these various kinds of relationships for loving our friend. That is, I may love my friend because of the pleasure I get out of her, or because of the ways in which she is useful to me, or because I find her to have a virtuous character. Given the involvement of love in each case, all three kinds of friendship seem to involve a concern for your friend for his sake and not for your own.

A friend, is one who (1) wishes and does good (or apparently good) things to a friend, for the friend’s sake, (2) wishes the friend to exist and live, for his own sake, (3) spends time with his friend, (4) makes the same choices as his friend and (5) finds the same things pleasant and painful as his friend.

However, friends do not merely have such similarities antecedent to their friendship as a necessary condition of friendship. Rather, friends can also influence and shape each other’s evaluative outlook, so that the sharing of a sense of value is reinforced through the dynamics of their relationship. One way to make sense of this is through the Aristotelian idea that friends function as a kind of mirror of each other: insofar as friendship rests on similarity of character, and insofar as I can have only imperfect direct knowledge about my own character, I can best come to know myself—both the strengths and weaknesses of my character—by knowing a friend who reflects my qualities of character.

This is a really great article I found is a philosophy website about friendship. I edited here and there. But the general idea is presented here. It is true that friendship and love is often confused. Love is something mutual. There should be a feeling that you cannot be able to live the rest of your life without the person you love. Some possessiveness and some jealousy here and there. But why not friendship? Nothing is wrong with friendship and love growing together mutually, right?