I usually get along with everyone so don't worry too much about tablemates. The only thing I worry about is being seated at a big table where everyone else is together. I requested a large table for an upcoming cruise with my husband and I'm PRAYING we're not seated as the last 2 seats with a group of 8 or 6. So far hasn't happened on a cruise but happens to us at hibachi ALL THE TIME and it's soooo uncomfortable to be the outsiders!
On a lighter note, on my first cruise one of the couples at our table broke up half way through the cruise (they were engaged!) They showed up night one happy enough but the next 2 nights argued through dinner, night after that were gone and by the 5th night just the guy was back. He said they'd broken up but didn't want to talk about it. We were all sooooo curious!