Any reason someone could give for why they love me renders me replaceable. For instance, if they love me for my appearance, intelligence, kindness, well, there's always someone more attractive, smarter, kinder. So, all things being equal, they ought to trade up to a better model if presented with the choice; or if God is the most perfect example of all desirable traits, then they ought to love God and no one else. I'd like to ask the panel: in contrast to loving someone because of some quality that they might or might not be the best exemplar of, does it at all make sense to love someone in their particularity, ie simply because they occupy a certain position in the time-space continuum? Or does that make a nonsense of the concept of love? Or is it silly, in the first place, to look for reasons for love?

I don't know about loving someone thanks to their position in the time-space continuum, but yes, we can and do love people for their particularity, as you put it. It's important to distinguish what sparks love for someone and what sustains it. It's certainly true that we cannot love just anyone. We vary in the traits we find attractive or lovable. When we first encounter someone, their attributes are what sparks our love for them. But love has a history, and as loving relationships develop or evolve, we often come to love someone less for their attributes than for the person that they are. It's then that the beloved seems irreplaceable, for only that person will have their distinctive set of attributes, etc. Christopher Grau's article "Love and history" (https://philpapers.org/archive/GRALAH.pdf) is very good on this subject. Bennett Helm's article on love in the Stanford Encyclopedia of Philosophy (https://plato.stanford.edu/entries/love/) is a good place to get a foothold on the philosophical issues...