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No, it is your choice but likely there will be other areas you can dine out on a fomal night. You will stll see those who do wandering about the ship and getting their photographs taken. The table you are allocated might mean you get on well with them and want to go, you never know but whatever enjoy your cruise.
On most ships the dress code applies to all bars and restaurants for the evening so unless you want to stay in your cabin, go on a ship that does not do formal such as Ocean Villag.
There are meetings on board for people travelling on their own. I would be prepared for going to a formal meal as you may find that a group you meet with regularly will go and if you are unprepared you can't join in. You can still opt out if you want too then. Just looking at your address a kilt and shirt counts as formal gear if you have it...Nei.