I'm single and live alone, and just about every holiday I've been on in recent years I've gone by myself. An English Heritage tour of the Welsh Marcher castles, a Nile Cruise, a "Solo" type holiday, and a couple of bog standard package holidays.
English Heritage tour was fab, everyone there had the same interests and we had good guides.
Nile Cruise was also good - I went with a smaller company so there was a group of about a dozen on the boat who in general got on very well and we had our own table for dinner so got to know each other. Went on most of the outings, and ended up chaperoning the youngsters (by choice) if their parents didn't want to go out.
Solo type holiday was also quite good, there was only one middle aged guy there who was obviously "on the catch", some people were singletons like me & others it was their choice or circumstances to go without a partner. Everyone knew that as we were all there alone, we should try to get along OK etc and that worked well.
The package holidays have been to various interesting places like Majorca, Morocco, Crete. All places where you can have outings with the tour company as you wish, plenty of interesting places to go, and in the safe environs of the hotel so fewer worries about being a single woman alone in a foreign country. Made really good friends with the tour guide at one, & we chatted in the bar or by the pool most evenings. The staff tend to notice if you're always alone & keep an eye out if it's a decent hotel, and in one the head waiter sort of adopted me as someone he took special care of because I was alone (no he wasn't coming on to me either!). My Kindle was my best friend on these holidays.
Go for it - I loved every minute of mine and got to see some incredible sights and enjoy different cultures. Just wish my health allowed me to still do this.