Kudos for mentioning the Cathars, always a big plus in my book, but this paper seems to be making a circular argument based on a questionable definition of romantic love. The argument seems to be that based on the definition that romantic love is selfish and exclusive, it is immoral or at best amoral because being selfish and exclusive is immoral. This also seems to presuppose that romantic love precludes other forms of human interaction. Unless we take Dante's description of the second circle of hell as a moral standard, that assumption has little justification.

The troubadours, like the Sufi poets, used the language of romantic love to describe love for the divine and the Creation that includes fellow people. One can feel romantic love for everyone, as some have described agape, and even if one reserves romantic love for a significant other, they can still feel love for others. Monogamy (as normally defined) is exclusive, yes, but that is not the same as selfish. Would we argue that if you aren't friends with everyone that one is selfish?

The mention of the materialist reduction of love to biological imperatives doesn't strengthen the argument. People can clearly reproduce without any form of love, and people can have a romantic relationship without reproducing. The suggestion that reproduction in technologically developed countries can be considered immoral is a non sequitur.