The four loves come from the Greek who use four words to describe what we use one for.
Storge: Affection Love
Phileo: Friendship Love
Eros: Romantic Love.
Agape: Divine Love.
Storge Love: [The frosting on the cake] Affection is the most humble of the loves. It is the love of enjoying someone or something. Storge is the joy in seeing Les Miseribles. Liking this play can be a sort of this love. Also for people, it can be the enjoyment of their company, whether they believe what we do or not. Ice-Cream, watching 24 the series, being with good friends, quality as Storge love. Now this kind of love is the jacket that clothes the other loves that we may enjoy them. But even in this innocence there is the danger of selfishness. Of hoarding something or someone to their pain, or to ours.
Phileo Love: [The punch on the side] Friendship is the least needed says Lewis of the loves. This is the least jealous of the loves. “Friendship arises out of mere companionship when two or more of the companions discover that they have in common some insight or interest or even taste which the others do not share and which, till that moment, each believed to be his own unique treasure or burden.”
This friendship is pointing somewhere, going somewhere, while Eros points the people at each other Phileo points them toward that certain goal.
Funny that Lewis also states that if a male and female of same interests and goals, who are not repulsive to each other and love no one else, will eventually grown into Eros love. There is no true “friendship,” for single males and singles female for Lewis, who get too close. But although he speaks of this love as the least needed, it seems the most enjoyed and the longest lasting of the earthy loves.
Eros Love: [My cake!] This is also the love that creates the hottest of fires in our emotions. It can be a wonderful light, or a scorching fire. Romantic or erotic love: Lewis calls this “being in love.” Now there is a difference in being in love and “falling in love.” You can control the former but not the later one. It is the love that is least thought about but most felt. It will be completely destroyed says Lewis as destroying the mountain view when you locate it in the retina or by asking too many questions! It is sexual and not. It seeks one and only one person. “The fact that she is a woman is far less important than the fact that she is herself.” This love does not aim at happiness, but on a particular person at all cost. “Better to be miserable with her than happy without her.” He writes:
“When the two people who thus discover that they are on the same secret road are of different sexes, the friendship which arises between them will very easily pass – may pass in the first half hour – into erotic love. Indeed, unless they are physically repulsive to each other or unless one or both already loves elsewhere, it is almost certain to do so sooner or later. And conversely, erotic love may lead to Friendship between the lovers. But this, so far from obliterating the distinction between the two loves, puts it in a clearer light. If one who was first, in the deep and full sense, your Friend, is then gradually or suddenly revealed as also your lover you will certainly not want to share the Beloved’s erotic love with any third. But you will have no jealousy at all about sharing the Friendship. Nothing so enriches an erotic love as the discovery that the Beloved can deeply, truly and spontaneously enter into Friendship with the Friends you already had; to feel that not only are we two united by erotic love but we three or four or five are all travelers on the same quest, have all a common vision.”
Agape Love [You may take my cake]: This is the highest and most unselfish of the loves, the love the Apostle Paul talks about in 1 Corinthians 13. It is also called Charity. It is not natural, it goes against our very natures. It loves the unlovable, undeserving, the ugly. It gives all and asks for nothing in return. It is the one that takes the greatest chance. And is hit with the most loss.
This is our choice, take a chance, tis better to love and die, than to not love and cry. God is Love, and that love we all will slowly develop as we grown in Him: We begin to change from natural to supernatural.
It is a wonderful thing to have all four of the loves aimed at one person–in an ideal marriage. But they must fall in order, lest we treat them as a means and not an end.
Agape is, by its definition, the highest and most unselfish of the loves. It is not natural and goes against human nature. Lewis pens a poetic image of the suffering of Agape:
To love at all is to be vulnerable; love anything, and your heart will certainly be wrung and possibly be broken. If you want to make sure of keeping it intact…you must give your heart to no one, not even to an animal…lock it up safe in the casket or coffin of your selfishness. But in that casket-safe, dark, motionless, airless–it will change. It will not be broken; it will become unbreakable, impenetrable, irredeemable. The alternative to tragedy, or at least to the risk of tragedy, is damnation. The only place outside of heaven where you can be perfectly safe from all dangers and perturbations of love is Hell.
According to 1 John 4:8,16, God is Agape, and that love we all will slowly develop as we grow in Him. However, Lewis also points out that although God is love, love is not God. He says that if any type of love became a god, it would, in fact, become a demon, seducing our souls toward despair and death. 
Agape is the most often-used Greek word for love in the New Testament. Contrary to popular understanding, the significance of Agape is not that it is an unconditional love, but that it is primarily a love of the will, rather than of the emotions. New Testament scholar D.A. Carson argues it is not as “uncondtional as we think:
The Lord Jesus commands his disciples to remain in his love (John 15:9), and adds, John 15:10, ‘If you obey my commands, you will remain in my love, just as I have obeyed my Father’s commands and remain in his love.’ …We may ask ourselves how well certain evangelical clichés stand up… ‘God’s love is unconditional,’ doubtless that is true…with respect to God’s elective love. But it is certainly not true [in] God’s discipline of his children means that he might turn upon us with the divine equivalent of the ‘wrath’ of a parent on a wayward teenager. Indeed, to cite the cliché ‘God’s love is unconditional’ to a Christian who is drifting toward sin may convey the wrong impression and do a lot of damage. Such Christians need to be told that they will remain in God’s love only if they do what he says.
Although God loves the sinner in the general sense, he has a special love for his redeemed people that is filled with Eros-type desire for them.
In all, it is one of my favorite books Again Lewis amazes me, and inspires me in his work.