There are no limits on true self-giving. It is not just to those one likes that one makes the offering. This involves a love that issues from the very CENTER of the person's being, directed to the CENTER of the other person's being, a love that gives ALL that the person is in order to foster the other person's life, a love that is offered to EVERYONE, without exception and without condition. The love is not offered to people because they are one's friends; people become "friends" because one loves them.
Ultimately, we have just one moral duty: to reclaim large areas of peace in ourselves, more and more peace, and to reflect it toward others. And the more peace there is in us, the more peace there will be in our troubled world.