Two excerpts by Fromm

Love for one person implies love for man as such. The kind of "division of labor" as William James calls it - namely, to love one's family, but to be without feeling for the "stranger," is a sign of a basic inability to love...


It appears from what has been said that love cannot be separated from freedom and independence. In contradiction to the symbiotic pseudo-love, the basic premise of love is freedom and equality. Its premise is the strength, independence, integrity of the self, which can stand alone and bear solitude. This premise holds true for the loving as well as for the loved person. Love is a spontaneous act, and spontaneity means - also literally - the ability to act of one's own free volition. If anxiety and weakness of the self makes it impossible for the individual to be rooted in himself, he cannot love.
This fact can be fully understood only if we consider what love is directed toward. It is the opposite of hatred. Hatred is a passionate wish for destruction; love is a passionate affirmation of its "object".12 That means that love is not an "affect" but an active striving, the aim of which is the hapiness, development, and freedom of its "object." This passionate affirmation is not possible if one's own self is crippled, since genuine affirmation is always rooted in strength. The person whose self is thwarted, can only love in an ambivalent way; that is, with the strong part of his self he can love, with the crippled part he must hate.13

(...)
The important point, however, is that love for a particular object is only the actualization and concentration of lingering love with regard to one person; it is not, as the idea of romantic love would have it, that there is only the one person in the world whom one could love, that it is the great chance of one's life to find that person, and that love for him or her results in a withdrawal from all others. The kind of love which can only be experienced with regard to one person demonstrates by this very fact that it is not love, but a symbiotic attachment. The basic affirmation contained in love is directed toward the beloved person as an incarnation of essentially human qualities.
Love for one person implies love for man as such. The kind of "division of labor" as William James calls it - namely, to love one's family, but to be without feeling for the "stranger," is a sign of a basic inability to love. Love for man as such is not, as it is frequently supposed to be, an abstraction coming "after" the love for a specific person, or an enlargement of the experience with a specific object; it is its premise, although, gentically, it is acquired in the contact with concrete individuals.

“Selfishness and self-love“
Erich Fromm.