Thanks for responding! I hope you have the patience to help me understand a bit more. :)

Of course! Thanks for asking and being open ☺

E.g. in academia (at least in my country) we tend to talk about authors of a particular paper as "they" whether they are one, several, male, female etc, even if you know their gender. It is consided respectful, unassuming and inclusive.

Yeah I think this is totally normal and okay, but if the particular paper in question, e.g., is about gender, and the author writes about their unique gender, I think it would be inappropriate/disrespectful to not use their preferred pronouns°

Do you think it is disrespectful to e.g. say "I love my partner, they bought me legos for christmas" when talking about my spouse to a colleague even I know she's female? Where my motivation is to not have gender in the conversation?

It definitely depends on the person and the culture. Some people, cis or not, feel a strong internal sense of their gender, and may feel misrepresented when referred to with neutral pronouns. (Further reading °if I were writing a paper and referenced this author, I would be sure to use Their preferred pronouns, because Their pronouns are known and relevant (They/Them, Capitalized))

I'm quite queer and have facial hair, so when I refer to my partner with neutral pronouns, people assume she's a man, and then she has an uncomfortable first interaction with those people when they meet her, and wonders if I'm embarrassed to be in a relationship with a woman.

Personally, if I hear someone specific being referred to with they/them pronouns when their preferred pronouns ought to be known, I assume they're non-binary, trans, or at least some sort of queer

Ultimately, 'they/them' pronouns aren't entirely neutral. Those pronouns imply personhood, can strip away identity from some, and are an identity for others