While studying philosophy in college, I was given the opportunity to have a research project supported by the University. I had been working with a professor on moral psychology of guilt, contempt, resentment, and indignation, so I wanted to carry over much of what I had learned there into another emotion with a lighter side -- romantic love. What I found at every turn was surprising and disappointing at the same time. There was little research on the matter from an analytic perspective and what few pieces I could find (here, here, here for examples) were seriously undertreated when compared to the literature on contempt, resentment, guilt, jealousy, apology, and other major emotions (with the exception of this piece, which I found one of the more informative).
Why could this be? Why would professional analytic philosophers appear to shun what is arguably the most important emotion in most people's conceptions of a good life? It isn't that they don't have the analytic tools and background to analyze what is clearly a loaded emotion -- there is plenty of excellent literature on contempt, guilt, resentment, apology, penance, and similar emotions. And why was it that the few examples there are are so abstract that it appears they aren't even talking about the same attitude or emotion most people would identify as love? It isn't just that that's how moral psychology works -- if you look at literature for similar emotions and attitudes you'll find that it is surprisingly well-grounded in common-day experiences.
I think there are at least four reasons why academic philosophers aren't more interested in grappling with the moral psychology of romantic love.
Not Niche Enough
It's no secret that to survive as a graduate student and a non-tenured professor in academia you must carve out a highly niche area in your discipline and develop yourself as one of the leading experts in that niche area. This means not only looking at a part of your discipline (i.e., in philosophy this would be ethics, political philosophy, metaphysics, aesthetics, or epistemology), but then looking at a part of that subdiscipline (e.g., moral psychology under normative ethics in philosophy).
The philosopher I studied with, for example, developed herself as one of the leading experts on the moral psychology of hope. While this might sound as broad as the moral psychology of love, it's much more niche. Think about all the uses for the word "hope" -- all the stories in which it is employed, the contexts in which you can use it, and what it means to most people. It's likely much more limited than doing the same for "love." Love inspires entire genres of art, poetry, literature, and theatre. The history of romantic love runs much deeper and is much more tumultuous than most emotions or attitudes. Some histories of romantic love have it dating back to the courtship practices of the Crusades, where lords and aristocrats would go off to war, leaving their wives home to be courted by other men, while others have it only dating back to the rise of capitalism, which disrupted standing class norms enough and freed up enough time from basic farming to allow people to pursue those in whom they were actually interested.
Regardless of the actual evolution of romantic love, a fair and good philosophical treatment would want to take this into account. Any analysis of romantic love as an emotion or an attitude would likely be interdisciplinary -- pulling on depictions through literature, theatre, the real world, and through empirical research (something analytic philosophers are largely opposed to citing in their work).
At the same time, research on the moral psychology of romantic love can be considered too niche. As noted above, the evolution of romantic love as a concept is contested in western culture. What it means to be in love in 2015 is different than what it means to be in love in 1955 is different than what it means to be in love in 1815 is different than what it means to be in love in 1615. Although the cultural norms and mores that govern our emotions and attitudes in general evolve over time, what it means to be in love with somebody probably shifts more than what it means to feel guilty about something or to be contemptuous of somebody.
So any treatment of romantic love as an attitude or an emotion would either have to be so generic and broad that it included love in 1815 and love in 2015 or it would have to be so narrow and niche that it might not be relevant in 30 years. Some treatments 45 years ago might not have included homosexual love or interracial love, showing the potential shortsightedness of writing on this topic.
Even more, romantic love is probably more culturally relative than something like guilt or contempt. While what may stir up guilt or contempt changes from culture to culture, they're largely universal emotions that can be recognized through universal facial expressions. Romantic love, on the other hand, is probably much harder to recognize outside of liberalized, western nations. Arranged marriages in the east clouds the formal institutions that encapsulate romantic love in the west. Culturally acceptable polygamy in some countries and cultures throws off the incentives aligned by respect for monogamy in the west.
This doesn't mean a useful and insightful analysis can't be posed -- simply that it would be unlikely to garner much attention in academia or carry the weight necessary for a young, ambitious academic to keep it moving.
Fear of Becoming a Philosopher King
Posing a philosophical analysis of romantic love will undoubtedly require you to cut some people's definitions of love out. Even if you are only making a descriptive case (in contrast to a normative case), you cannot include everybody's definition of what romantic love is within it.
This makes most people uncomfortable, and philosophers aren't excluded from this category.
Writing an analysis of romantic love that is both useful and insightful while also not excluding large swaths of the population is tricky, if not impossible. Philosophers, already accused of being detached from the real world and working from an ivory tower, are unlikely to engage in an analysis that will either isolate large groups of people or will potentially offend peers (thereby hurting their chances of getting their work published).
Thinks Themself a Philosopher King
On the other side of the coin, there are philosophers who are so happy to stay detached from people outside academia and people outside the discipline that romantic love just seems like a boring topic or too layman for the successful academic. A good descriptive case of the moral psychology of romantic love would benefit greatly from empirical studies and research, but such research in positive psychology is viewed by analytic philosophers as on par with pop psychology and avoided if you want to be taken seriously as an academic.
By "Thinks themself a philosopher king," I don't necessarily mean the opposite of the prior conjecture. Rather, I mean that they think that they are above doing pop philosophy, or doing philosophical work that is actually applicable to the lives of everyday people. If that's the case for some philosophers, that's a shame, because philosophy is one of the most useful tools for any person trying to live with integrity.
It might simply be that the incentives within academia aren't aligned for real-world philosophy on subjects that people care deeply about. It may be that the best ways to approach these subjects are outside academia. Using the research from academic philosophers and the tools given to us by studying philosophy, non-academic philosophers may be those best equipped and in the best institutions to deal with these issues.