I am a 47 year old woman and I have been on lots of cruises alone and with people and they both have their benefits. I know the feeling of sitting at the table with all couples and you are the only single persn; it get kind of uncomfortable. What I used to do sometimes when I went alone was to go to the buffet , which has the same food as the sit down dinner, and eat by myself so that I didn't feel uncomfortable.
On another cruise, I asked to sit at a singes table, and I had the time of my life. We were about 12 people, men and women and we had a great time every night.
People on cruises are very friendly and you will have a great time either alone or with someone.
I would love to help you with any other stuff you might need.