It's good that you are accompanying your spouse, although it is not necessary and the vo likely won't ask you any questions (some do, but it is rare), but it looks very good to be there supporting your spouse. My advice to the spouse undergoing the interview is: don't be nervous, even if they answer some of the questions wrong (although not ideal, but it happens), the vo goes off of body language and how the question was answered, so if your spouse is hesitant, anxious, unusually nervous, rude or dismissive, things like that, then that could make the interview unsuccessful. Your spouse should be confident and answer every question to the best of his knowledge (even if he gets some questions wrong) as long as he comes across as genuine, then you should be ok.
Most of the people I know who have had interviews have been successful ( and yes some of them got questions wrong). A good thing to do is order your notes to see why you have been selected for an interview. When is your interview scheduled?
