Learn English – Slang words for person who is bad at language

In the UK, posh is used primarily by working class people. It is used by aspirational ones in a positive way, "we got dressed up all posh, like", but it can also have a derogatory meaning. If you offered a napkin to a proud-to-be-working-class man, he might reply

Naa, I'm not posh, mate.

ladida is a mild expression of disapproval of somebody's affectations.

poncy is a working class way of saying "pretentious", and it's definitely derogatory. This might be used about the shirt:

You won't catch me wearing a poncy shirt like that!

I think you are right that jealous and possessive are the two most appropriate words. Yes, they do both have negative connotations, but a complete absence of jealousy can be regarded by a person with a negative outlook as uncaring or unemotional, and by a person with a positive outlook as trustful or trusting.

In western society, it seems that both men and women are expected to show occasional signs of jealousy, but they are expected to keep their anger in check.

If a person knows that their partner is having sex with other people, they might be called broad-minded. This term has both a specific meaning relating to sex and a more general meaning: the context would indicate which meaning is intended.