On some union models of love, like Robert Nozick’s, our well-being extends to include our beloved: good and bad things happening to our beloved count as happening to us.
A standard criticism of the union models (I first saw it in Jennifer Whiting’s criticism of Aristotle) is that we end up pursuing the other’s good not for their sake but for our own, since their good is a part of our well-being.
This criticism seems to me to only apply if one adds to such a union model the thesis that our actions are always solely in pursuit of our own good. But such a thesis leads to the problem that we don’t pursue other people’s good for their own sake independently of the union of love. The criticism, thus, is not a criticism of the union model of love, but of an egoistic theory of motivation.
The fact that the other’s good is a part of my good does not entail that I pursue the other’s good because it is my good. After all, we sometimes do things that we know benefit us but do them for reasons other than the benefit to ourselves. If after adding up the scores, I see that I am the winner of a game, my announcing the scores benefits me. However, I do not announce them because this benefits me, but because it’s the truth.
It is true that if I were omnirational, and if my own good were not excluded by a higher-order reason, then whenever an action benefited me, that benefit would be a part of my reasons for the action. But that is not objectionable: on the contrary, it is a part of the charm of love that the lover acts not just for the sake of the beloved but also for their own sake. That fact helps make the lover’s generosity not be a demeaning condescension.
Perhaps the criticism comes from a deeper mistake about love, the mistake of thinking that when we act lovingly, then typically the love is itself a part of the reasons for the action. For if the love is constituted by the other’s good being included in mine, and if the love is a reason for the action, then it does seem that when I act because of the love, I act because of the other’s good being included in mine. However, typically when we act lovingly, we do not act because we love. If my friend needs help, helping them is loving, but to reason “I love, so I should help” is to think a thought too many. Instead, one should just reason: “They need help.” My antecedent love makes it more likely that I will act on that reason, and my acting on that reason is partially constitutive of the continuation of the love, but the love is not itself the reason. After all, imagine that five minutes before finding out that my friend needed something, I stopped loving them. That would be no excuse not to help!
In fact, it seems to me that the best kind of union model would say something like this: What makes it be the case that my beloved’s good is a part of my good, what makes my beloved be “another me”, is the fact that I am pursuing my beloved’s good for their own sake. In other words, one could hold that love is constituted by union, but the union is constituted by pursuit of the beloved’s good.