My brother is annoyed that I have learnt his wife's language

[poochuspoochus]

My brother got married yesterday and they have been together for seven years. I really love languages and although it wasn't a language I knew at all before I was introduced to his now wife I find it to be a really interesting one. So over the last seven years I have picked up enough to be able to speak quite well coversationally. I don't think he realised how much I had picked until yesterday as we are in sil's country for the wedding. He has sent me a message this morning saying it was a bit weird how I have attached myself to his wife's culture and he thinks I am obsessed with his family. Firstly why is he worrying about this the day after his wedding. Also I really wasn't making a big show of speaking the language just chatting to people normally. There's really no backstory to this as far as I'm aware. I really don't him to be upset but he's the one being weird isn't he?

Lol what? Some wild assumptions here.
Why should OP apologise for making an effort to learn a language? Was she supposed to pretend to be a mummy because it was 'his day'?
He's a jealous a hole and he made himself look bad. If he is bothered and feels insecure, he can easily pick it up now himself and excel at the language i na few years time.

Sorry it wasn’t clear!

The first line was kind of disagreeing with you, because OP didn’t only learn from Duolingo and could have made better progress practising with the friend.

I agree with the rest of your post. It was odd for the OP to put in all that effort for a minimal return, so, weird; or OP wasn’t really all that fluent.

I also think this Great Reveal at the wedding would have been awkward and discombobulating for the groom, and that’s what my two main paragraphs were about. Should have put them in a separate response rather than replying to you

From which linguistic family is the language?

Something difficult for westerners, perhaps tonal, like Thai or Cantonese? Or something simple to learn at least a little of, like French?

Theres no excuse for the husband not learning something like the latter.

I think it’s a lovely thing to do tbh. If you’ve the time, why not.
If it were me (sil), I’d be touched that you took the time. The disadvantage is that she can’t talk about your family with her family over the phone in your presence 😛

Your brother probably feels like you’ve shown him up. He’s the one with her and hasn’t made enough effort or has struggled to learn the language. He’s jealous.