If it is the first week of your trip - Take it easy, the van is a small place and teething problems are completely normal. We are confident you will work things out and you will all be cool calm and collected by week 2 of your holiday. Do something fun to break the tension!
If you have already travelled for 3 weeks - You have given this a fair chance. Look for viable exits. Please bear in mind early return of your campervan is not refundable.
On your honeymoon? - We can't help you. You signed up to this for the rest of your life.