Normal
We sat with a pastor and his wife on one cruise - table for 10. They just quietly prayed together while the rest of us chatted away. I wish they would have asked if the rest of us would join them...but they didn't. They weren't at dinner every night and often came in late. If someone at your table (should you not get one for two) has a problem with it check with the Maitre'd to see if any other tables are available. As long as you aren't in shorts, I don't think they'll turn you away from the dining room....even on formal/elegant night.