The Couple at the Table

You're on your honeymoon at an exclusive couples-only resort. You receive a note warning you to 'Beware of the couple at the table nearest to yours'. At dinner that night, five other couples are present, and none of their tables is any nearer or further away than any of the others. It's as if someone has set the scene in order to make the warning note meaningless - but why would anyone do that? The impossible to solve murder mystery.