I've seen the whole TNG series, I know the episode very well :p

I'm not sure it's too necessary for genders to be verbally declared for bumans and lumans, or at least I hope it isn't, but that's something I think I'll discover when I construct their languages.

When I was creating the three major races for my world, I tried to make them each as unique as possible, so they were easily differentiated on sight and by culture, but they didn't fall into the cliche traps it's all too easy to land in.

The tumans are not just romantic, but introverted and solitary much of the time, so their list of friends is very small, but they hold a deep affection for them. Their art comes in the form of solitary activitives, where only the end result is shown, such as writing poetry, painting, or creating gifts (this is as opposed to performance art, for instance, which would be rather embarrassing to a tuman). Clay is a major commodity on their homeworld, so they learn pottery and ceramic skills, so a quality vase is considered a lovely gift. They have specific courtship rituals involving gift exchange. When two tumans decide to be wed, part of their engagement period involves building a house together.

(Actually, that last sentence I just made up now on the spot, but I really like it, so it's canon now!)

Lumans and bumans, however, are polyamorous, but in different ways.

Lumans live in households of about three to six adults, which can have any ratio of men to women. They can certainly be loving, but they are more extroverted than lumans and have many friends and acquaintances. Their art is typically performance driven, so dancing, storytelling, playing music, and even cooking are considered great social forms of art.

Bumans are on the far end of the spectrum from tumans. They are polyamorous to the point of having no single mate or mates, but rather they take the concept of "it takes a village to raise a child" rather literally. A tribe or village is the smallest familial unit bumans care about. They are extraordinarily extroverted, humorous, and have no concept whatsoever of privacy or private property. What is made by one buman is meant for the tribe, so the tuman concepts of monogamy, gift-giving, and the like are very foreign concepts.

The varying customs of the races does have the potential to create some conflict, whether serious or playful, but, being that this world is made for a tabletop RPG, it's up to the players to decide how they'd like to play their characters. They might ignore those differences to focus on the external quest, or they might make internal conflicts the central focus of their game.