"Я не хочу у вас жить" - why "у вас"?

Question

In the phrase "Я не хочу у вас жить, когда я буду в Москве" I would expect an instrumental case, for example with preposition c, but why actually preposition y is used?

Answer 1

The verb жить can be used to answer the question - 'С кем ты будешь жить?' (with whom will you live?) - in that case indeed it will be "я не хочу с вами жить".

But the other question is "у кого ты будешь жить?" (roughly, at whose [place] you gonna live).

The difference between "жить с" and "жить у" is that the first one is something more fundamental. "Жить с кем-то" - implies some sort of long-term relationships of some kind - like "жить с родителями", "жить с девушкой".

One can say "жить у девушки", "жить у родителей", that's both grammatically correct and used form, but, however, when you are talking about some shirt-term event, say you want to visit your uncle, you'll probably will say something like "Я жил у дяди пару недель", but "Я жил с дядей пару недель" will sound slightly off to Russian speaker.

Also, there's form "пожить у кого-то" (but rather not "пожить с кем-то") - the "по-" suffix here indicates some short action.

Answer 2

Я не хочу у вас жить = I do not want to live at yours. (that is in his/her home but maybe agree to live together in a hotel)

Я не хочу с вами жить = I do not want to live with you. (in any place, including a hotel or dormitory)