Erik...as for dining alone you can see the Matre D when you get on the ship. You can ask to be seated at a table for 2 but do not do this a the dinner hr. Do it before hand. Dining with other passengers is something I look forward to. We enjoy conversing with others and find out how they enjoy their cruise and what they do on their cruise. I am surprised that you do not like this.
My first experiance in Holland was at a restaurant. There were 6 of us at a table for 8. Half way through our dinner in older gentleman came into the restaurant with his dog and sat at our table. Not speaking the language and being new to the Country what could we say? There were plenty other empty tables available. We found this a common occurance at McDonalds which always seemed to be packed when we went. I learned...if you can't beat them join them!
I would suggest that you dine at the table you are assigned the first night. If you do not enjoy your table mates then difinitely see about being changed the following day. On our last cruise we were seated with a lovely couple from England. I looked forward to dinner every night to visit with them. They were so delightful and always had so much to talk about. They would tell us about their days excursions we we would tell them about ours.