Tablemates can certainly make or break your cruise. More recently you can see the increase in tables for 2. I have not been on Celebrity, but, would definitely visit the Maitre D on the first day & place a request.
Often I travel alone, as I go to visit friends that work on the ship. I have had the priviledge to meet some fabulous friends who I have been seated with. In fact 2 years ago I was placed at a table for 10 on a 14 day cruise. At first I was like, wow, this is too many people! But, we all hit it off so well we have planned a cruise reunion together!
Anyways, good luck & have a wonderful cruise