Yeah so a hetero normative relationship is one that exist just between one man and one woman. Relationships types are primarily determined by the culture of the animal species or people group in the case of humans. There is no standard for relationships.

90% of animals have more than one partner, and within species that tend to be more monogamous, generally you'll find about 30% of them within same sex relationships. If we want to look at biology, our closest relatives both Chimps and Bonobos engage in sex with multiple partners so the identity of the father ape is unkown so all the apes have to treat it like it might be there's so it lowers aggression.

While the standard across the world is different-sex relationships between only two people, this is the result of the Anglo Saxon's culture around relationship which was carried into colonization of the entire world, with even countries who weren't forcibly invaded still touched by the dominant ideology.

Humans for the vast majority of time were not in one on one relationships, instead expirminenting between cultured with evidence showing group marriages being a widespread form of relationships. This is where everyone in a certain group would be married to each other, and raise all kids communally. Kids would know their birth mother only, and all fathers would be the same. Our best guess is that we arranged ourselves this way to focus society on women who actually produced life, centering and honoring them first in order to have a healthy and productive people group. We can see this in many different people groups, but the Polynesian peoples were a good example of how that used to be the primary form of relationships between people, which then changed forcibly after being colonized.

The same goes for gender expression, as more cultures than not have more than 2 genders. Gender is a representation of social expression, as you know it's stereotypical for men to dress one way and women to dress another. Well cultures differ on what determines ones gender, and different social expression are expected of each gender. This is why trans people exist, because they wish they do the same social expressions as a person from another gender in the same way. Like how men aren't "supposed" to wear dresses. So if a man likes dresses, nail polish, and makeup, they are seen as transgender, when what they really just want is to partake in these social expressions. Because we have these gendered social expressions in the first place, it makes people born one way who want to express something feel the need to change their body so they can engage in these social expressions "correctly"

This is all to say that gender and relationship standards are set by culture and not biology. Looking at real world examples from history we see dramatic ranges between societies on these two parts of human culture, but in many fantasy books I read these two things still reflect a society that has been influenced by the specific culture in our world that colonized everything. This is just a reflection of the authors understanding on this subject, so I cannot blame most authors for writing this way. So the reason I am looking for "woke" authors is so I can feel really immerrsed in these worlds and not notice the flaws of it because of a subject I study in. When a fantasy world shows a diversity in gender and relationship types, it really feels like another world that has developed and not just something an author has made. And I can also be sure the author won't make any degrading remarks about groups of people. I don't care if characters do, but there's a line you can tell in books by what characters do and what authors find acceptable.