Why, after first admitting to himself that Daisy "might have loved [Tom] just for a minute, when they were first married," does Gatsby say, "in any case, it was just personal"?

This remark is overwhelming in its intellectual audacity: when he is forced to admit that his lost Daisy did perhaps love her husband, he says, "In any case it was just personal." With that sentence he achieves an insane greatness, convincing us that he really is a Platonic conception of himself, really some sort of Son of God.

This statement that Gatsby mkes to Nick the morning after Gatsby waited until 4 o'clock watching over Daisy and waiting for her signal that never came, attests to Gatsby's greatness. What he means by this statement is that Tom and Daisy's love was just sexual; it was just a meeting of bodies and not to be compared to the ideal, Platonic love that he and Daisy shared. This statement is intended to contrast to Tom's view of love when Tom and gatsby confront each other in the hotel room in New York City. When Gatsby proclaims his love for Daisy, saying that he and Daisy loved each other for five years and that Tom didn't know, Tom immediately asks if they have been seeing each other all that time. Gatsby says that no, they could not meet because he was off fighting in the War, but that they loved each other just the same. Tom's reaction is to breathe a sigh of relief, for he defines love only in terms of sex. He cares little that Gatsby loved Daisy in his mind; he cares only that they did not have a sexual relationship during that time:

“Sit down, Daisy.” Tom’s voice groped unsuccessfully for the paternal note. “What’s been going on? I want to hear all about it.”

“I told you what’s been going on,” said Gatsby. “Going on for five years—and you didn’t know.”

Tom turned to Daisy sharply.

“You’ve been seeing this fellow for five years?”

“Not seeing,” said Gatsby. “No, we couldn’t meet. But both of us loved each other all that time, old sport, and you didn’t know. I used to laugh sometimes”—but there was no laughter in his eyes, “to think that you didn’t know.”

“Oh—that’s all.” Tom tapped his thick fingers together like a clergyman and leaned back in his chair.

Of the four rungs of the Platonic ladder of love - Divine Love, Aesthetic love (the love of beauty), Platonic love (friendship) and sexual love, Gatsby has achieved the highest rung - Divine love - while Tom remains on the sexual level, the lowest rung.

According to Plato, sexual love occupies the lowest rung on the Platonic ladder since it is directed merely toward the gratification of the body. Although sexual intimacy is an important dimension of love, the Platonists claimed that the mature individual begins to adopt a more responsible moral stance and to pursue the higher forms of love, since sexual love, by itself, is incomplete and therefore unsatisfying. This idea is emphasized in a number of Platonist treatises, one of the more popular being Baldassare Castiglione’s The Book of the Courtier. In his discussion of the Platonic ladder, Pietro Bembo, the most prominent character in Castiglione’s Courtier, says that whereas the passions are often responsible for directing the actions of youth, such passions must be controlled as one advances in age; the older a person becomes, the more that person must act according to the dictates of reason and according to those laws that govern proper conduct and the attainment of the moral good:

…I think that, although sensual love is bad at every age, yet in the young it deserves to be excused, and in some sense is perhaps permitted. For although it brings them afflictions, dangers, toils… still there are many, who, to win the good graces of the ladies they love, do worthy acts, which (although not directed to a good end) are in themselves good; and thus from that great bitterness they extract a little sweetness, and through the adversities which they endure they finally recognize their error. Hence, even as I consider those youths divine who master their appetites and love according to reason, I likewise excuse those who allow themselves to be overcome by sensual love, to which they are so much inclined by human weakness: provided that in such love they show gentleness, courtesy, and worth… and provided that when they are no longer youthful, they abandon it altogether, leaving this sensual desire behind as the lowest rung of that ladder by which we ascend to true love. But if, even when they are old, they keep the fire of the appetites in their cold hearts, and subject strong reason to weak sense, it is not possible to say how much they should be blamed. For like senseless fools they deserve with perpetual infamy to be numbered among the unreasoning animals, because the thoughts and ways of sensual love are most unbecoming to a mature age. (Castiglione, The Book of the Courtier. Anchor Books, 1959, 339-340)

Bembo’s words serve as a scathing censure of those like Tom Buchanan who are so morally bankrupt that they are condemned to remain forever on the lowest rung of the Platonic ladder.

Gatsby's capacity for love elevates him to heroic status and deems him worthy of the title ascribed to him, the "Great" Gatsby.