unconditional love

nostalgebraist argues that unconditional love can't and shouldn't exist:

A parent might love their child "unconditionally," in the well-understood informal sense of the term, but they don't literally love them unconditionally.  What could that even mean?  If the child dies, does the parent love the corpse -- just as they loved the child before, in every respect, since it is made of the same matter?  Does the love follow the same molecules around as they diffuse out to become constituents of soil, trees, ecosystem?  When a molecule is broken down, does it reattach itself to the constituent atoms, giving up only in the face of quantum indistinguishability?  If the child's mind were transformed into Napoleon's, as in Parfit's thought experiment, would the parent then love Napoleon?

Or is the love not attached to any collection of matter, but instead to some idea of what the child is like as a human being?  But what if the child changes, grows?  If the parent loves the child at age five, are they doomed to love only that specific (and soon non-existent) five-year-old?  Must they love the same person at fifteen, or at fifty, only through its partial resemblance to the five-year-old they wish that person still were?

Or is there some third thing, defined in terms of both the matter and the mind, which the parent loves?  A thing which is still itself if puberty transforms the body, but not if death transforms it?  If the mind matures, or even turns senile, but not if it turns into Napoleon's?  But that's just regular, conditional love.

A literally unconditional love would not be a love for a person, for any entity, but only for the referent of an imagined XML tag, defined only inside one's own mind.

To me it seems like what matters in practice is the perception the love is unconditional on the part of the person receiving the love. Psychologically, that perception creates a baseline knowledge that they are worthy, that they can never become unworthy. The fact that my parents' love would go away if I'm replaced by Napoleon doesn't really change that, since it would be Napoleon experiencing the loss of love, not me. This perception does rely on illusions about the nature of personal identity, on the part of both the lover and the lovee, but since most of us maintain those illusions most of the time, it's basically okay.

My dog's love for me is not literally unconditional, but it's robust to many of the things I can do that would otherwise cause me to question my own worth, so in a practical sense it's extremely valuable.

True unconditional love would be spiritual joy, the ideal loving-kindness that values all sentient beings equally.