First off, I was brought up bilingually so have some insight to this.
My friend was holding a small drinks get together at her flat the other night, to celebrate a big birthday.
She invited an old friend who is Finnish, who asked if her partner of 6 months could come (Finnish), my friend said sure no problem. She got a message asking if her old flatmate who is incidentally Finnish could come.
There were 2 others who were from all over Europe, including my friend's husband. So, there were 4 of us sat at one part of the room, and the three Fins sat as a trio on the other side of the room. Not once, all evening did they engage with anyone else and spent the whole night speaking Finnish. I tried speaking to them as I know one of them, and received a rather curt "Yes" and then they proceeded to talk amongst themselves again.
The Finnish couple brought food to cook in the flat as they hadn't had time to eat beforehand (drinks were from 9pm..), they did not clean up their plates or pans.
My friend was given a bottle of Dom Perignon for her birthday by her parents, and kindly shared it in small amounts between all. There was a bit left, as I had poured the champagne. The Finnish couple then returned from the dining room and I'm pretty certain she had filled her champagne flute all the way up.
After a few drinks we decided to leave for a bar as my friends husband wasn't feeling well, so left so he could sleep. The Fins then proceeded to say "oh we'll stay here", but I'm not sure if this was said in jest.
It really pissed me off that they had basically ruined my friends birthday drinks and so I tipsily told them they had been "Incredibly rude". To which they tipsily retorted that they didn't like the area that my friend lived in! (For context, it's in a nice area of North London think £1m+, but the Fins live in a council tower block)
Do you think speaking in another language to exclude people is rude? Especially when at a small gathering at someone else's house?