I'm thinking about keeping motivation and relationships.
Each term can bring up different topics. For example in motivation, there can be topics on: social anxiety, loneliness, financial stress, eating disorders, depression.
And relationships: body language, pickup, dating.
Since I'd like to treat both via Youtube, does it make sense to keep in the beginning only 2 main categories?
Describe your goal for categories, as a starting point.
Also answer where you'll define these categories.
You mention YouTube + you might mean content categories on a WordPress site.
If you're referring to a Website, also be sure to state whether you're primarily targeting natural search engine traffic or you're primarily using paid traffic.
Provide more context + likely someone can assist.