There are three primary systems of love in the brain, romantic attraction, sexual attraction, and attachment. The most common configuration of these three is that attachment comes from shared experiences and romantic attraction triggers sexual attraction.

In many people’s brains, these connections are less strong or only happen in specific circumstances. Ergo, asexual and aromantic people exist. These are the physical underpinnings of these feelings.

Then you have the normative idea of romance that insists that romance, sexuality, and attachment are the same things and that the absence of one or more implies that there’s something wrong with the relationship. There are plenty of people who, in terms of brain chemistry, resemble aroace people, but consider themselves “normal” and feel that those aspects of themselves are aberrations. In terms of neurodivergence, I find that people whose neurodivergence allows them to be less sensitive to social pressure will tend to see those differences as normal and good, so maybe that’s an aspect.

So “what is platonic love?” may be a question that can only be answered accurately in terms of subjective experience by the person using the term. Unless you’re using it in the context of a community who is consciously discussing and agreeing on these topics, it probably doesn’t have an agreed upon meaning.