We are now returning to the 18th century empirical approach with the new interest in the evolutionary basis of ethics, with 'experimental' moral philosophy and moral psychology. As a result, we understand better why moral formulas are experienced as ineluctable commands, even if there is no commander and even if the notion of an inescapable obligation is just superstition. So moral philosophy has made huge progress.
Moral theory develops from the divine command theory of medieval Christian philosophy, mixed up with a bit of ancient pagan virtue theory, to the purely secular moral sentiment and interpersonal reaction theories of Smith and Hume, to Kant's attempt to restore command theory but with something supersensible in the individual rather than God as the source of authority.
You can find many philosophy papers on the themes of 'love' and 'friendship,' most of which are cheerful and somewhat anodyne; you don't find many on the loss of friends, relatives, and lovers from death or alienation, though it happens all the time.
Oddly, since by now I've written quite a lot on early modern philosophers, I didn't care for the history of philosophy, which I thought dull and obscure, until I got a minor job writing articles for a children's encyclopedia in the history of science and began to make connections between science and philosophy.
