"Does he save your wife or do you save her?"
Translation:An sábhálann sé do bhean chéile nó an sábhálann tú í?
Thanks. I learnt my first Irish from a book where the personal pronouns, along with their emphatic forms, were among the first things that were taught, and as I also speak Italian (where emphasis on the pronoun is also marked, as unstressed subject pronouns are simply deleted), the use of ‘tusa’ here came naturally to me. Strange that Duolingo doesn’t accept this then.
sibh is plural - a group of people. The "you" in "your wife" is obviously singular.
If the first part of the sentence was "your mother", or "your cat" or "your house", where "your" could be plural, then you could say bhur máthair or bhur gcat or bhur dteach and sibh.