Here is another excerpt from Section 2.2. of my forthcoming One Body book.
One way love is humble is that the actions of love are not focused on agapê itself [...]. There would be something odd about a parent explaining why he stayed up the night with a sick child by saying: “I love my son.” Surely the better justification would be the simpler: “He is my son.” The latter justification puts the parent in a less grammatically prominent spot (“my” instead of “I”), and shows that the focus is on the son. Most importantly, however, the use of “I love my son” as a justification would suggest that if one did not love him, the main reason to stay up the night would be missing. But the main reason to stay up the night is that he is one’s son. That he is one’s son is also a reason to love him as one’s son, and that one loves him may provide one with a further reason to stay up with him. However, the main reason for staying up is not that one loves him; rather, the love, expressed in the staying up, is a response to a reason that one would have independently of the love. Thus, in an important sense, the parent acts lovingly—acts in a way that is at least partly constitutive of love—without acting on account of love. Love’s actions are not focused on love but on the beloved as seen in the context of a particular relationship.
However, to explain why we made some sacrifice for someone to whom we had no blood ties, we might well say, “I love him.” Nonetheless, I suggest, this may be an imperfection—it may be a case of seeking one’s own. Why not instead act on account of the value of the other person in the context of the relationship? It is true that love may be a central part of that relationship, but I want to suggest that love is not the part of the relationship that actually does the work of justifying the sacrifice. For suppose that I stopped loving my friend. Would that in itself take away my obligation to stand by him in his time of need? Certainly not. The commitment I had implicitly or explicitly undertaken while loving him, a commitment that made it appropriate for him to expect help from me, is sufficient for the justification. If I need to advert to my own love, then something has gone wrong.
Besides, there would a circularity in appealing to one’s own present love to justify one’s basic willingness to engage in loving actions for the beloved. For if one were not willing to do loving actions for the other, then one would not be loving the other, and hence a total failure to will to do loving actions for the other would not be a violation of love, for there would be no love there to be violated. Of course, such a failure might well be a violation of one’s duty to love the person (whether arising out of personal commitment, or a general duty to love everyone or some specific duty like those we have to our relatives), but that is a different issue. It is not love, then, that justifies the general willingness to act lovingly, but the value of the other and the kind of relationship that one stands in to the other apart from the fact of love.