A good place to make friends is in a group where you can do things together on a social level. If you have a particular hobby or sporting interest, that could be a starting point. Perhaps you could even take up a new hobby. If you attend a church where there are other single people they may have a singles group which meets regularly for fun and fellowship. Try to meet people at places where you enjoy being so that you can find someone who has similar interests and values as yours. Then as your friendship develops you can continue to do those fun things together.
Do sport :) Single people are more active! You can meet them in the gim or in the park jogging or cycling. Or you may just ask your friends to introduce you to nice single people from their acquaintances and they can give you in advance some information about their interests, hobbies, professional fields :)
There are some usual ways that people go about meeting singles in their local area. Some options are joining a dating website or church community of singles. There are also less direct, but possibly more enjoyable ways of meeting potential partners, though. Consider joining a book club that’s focused on love-related topics, signing up for hiking trips or community activities with an outdoorsmen’s group, or taking an adult education class at your local community center. That way, even if you don’t meet a lot of singles, you’ll have an enjoyable experience and make new friends that share the same interests.
It can be hard to make friends after a break up, divorce or death of a spouse. It is even harder when you are older and have children or other commitments. I am not sure of your circumstances exactly, but agree that it can be difficult. Firstly, how do you know if someone is single or r only separated from their spouse, or in a long-distance relationship? I would join as many clubs or organisations as I could where there are people who share the same beliefs or interests as you do. I would focus on making my life as full and happy as possible. I would volunteer to help at a homeless shelter or animal charity so that I am focussing on helping others. I am sure that you will find it easier to make friends when you feel fulfilled and content.