Kant wrote "on the most intimate union of love with respect in friendship" in _The Metaphysics of Morals_:
***** _Friendship_ (considered in its perfection) is the union of two persons through equal mutual love and respect. -- It is easy to see that this is an ideal of each participating and sharing sympathetically in the other's well-being through the morally good will that unites them, and even though it doesn't produce the complete happiness of life, the adoption of this ideal in their disposition toward each other makes them deserving of happiness; hence human beings have a duty of friendship. -- But it is readily seen that friendship is only an idea (though a practically necessary one) and unattainable in practice, although striving for friendship (as a maximum of good disposition toward each other) is a duty set by reason, and no ordinary duty but an honarable one. For in his relation with his neighbor how can a human being ascertain whether one of the elements requisite to this duty (e.g. benevolence toward each other) is _equal_ in the disposition of each of the friends? Or, even more difficult, how can he tell what relation there is in the same person between the feeling from one duty and that from the other (the feeling from benevolence and that from respect)? And how can he be sure that if the _love_ of one is stronger, he may not, just because of this, forfeit something of the other's _respect_, so that it will be difficult for both to bring love and respect subjectively into that equal balance required for friendship? -- For love can be regarded as attraction and respect as repulsion, and if the principle of love bids friends to draw closer, the principle of respect requires them to stay at a proper distance from each other. This limitation on intimacy, which is expressed in the rule that even the best of friends should not make themselves too familiar with each other, contains a maxim that holds not only for the superior in relation to the inferior but also in reverse. For the superior, before he realizes it, feels his pride wounded and may want the inferior's respect to be put aside for the moment, but not abolished. But once respect is violated, its presence within is irretrievably lost, even though the outward marks of it (manners) are brought back to their former course.
Friendship thought as attainable in its purity or completeness (between Orestes and Pylades, Theseus and Pirithous) is the hobby horse of writers of romance. On the other hand Aristotle says: My dear friends, there is no such thing as a friend!...
>From a moral point of view it is, of course, a duty for one of the friends
to point out the other's faults to him; this is in the other's best
interests and is therefore a duty of love. But the latter sees in this a
lack of respect he expected from his friend and thinks that he has either
already lost or is in constant danger of losing something of his friend's
respect, since he is observed and secretly criticized by him; and even the
fact that his friend observes him and finds fault with him will seem in
itself offensive.
How one wishes for a friend in need (one who is, of course, an active friend, ready to help at his own expense)! But still it is also a heavy burden to feel chained to another's fate and encumbered with his needs. -- Hence friendship cannot be a union aimed at mutual advantage but must rather be a purely moral one, and the help that each may count on from the other in case of need must not be regarded as the end and determining ground of friendship -- for in that case one would lose the other's respect -- but only as the outward manifestation of an inner heartfelt benevolence, which should not be put to the test since this is always dangerous; each is generously concerned with sparing the other his burden and bearing it all by himself, even concealing it altogether from his friend, while yet he can always flatter himself that in case of need he could confidently count on the other's help. But if one of them accepts a favor from the other, then he may well be able to count on equality in love, but not in respect; for he sees himself obviously a step lower in being under obligation without being able to impose obligation in turn. -- Although it is sweet to feel in possession of each other in a way that approaches fusion into one person, friendship is something so delicate...that it is never for a moment safe from interruptions if it is allowed to rest on feelings, and if this mutual sympathy and self-surrender are not subjected to principles or rules preventing excessive familiarity and limiting mutual love by requirements of respect. Such interruptions are common among uncultivated people, although they do not always result in a split (for the rabble fight and make up). Such people cannot part with each other, and yet they cannot be at one with each other since they need quarrels in order to savor the sweetness of being united in reconciliation. -- But in any case the love in friendship cannot be an affect; for emotion is blind in its choice, and after a while it goes up in smoke. *****
What do you say, my dear Jim?
Yoshie