I have never come across someone who actually wants to stay single forever so I can’t answer for certain, but I imagine there are a good few people in this world who choose to stay single their entire lives, and more power to them!
I know a few people who are perfectly happy and content being single ‘right now’, out of choice. They actively remain single , avoiding relationships, but these same people have exciting and busy lives, great careers and amazing social lives, so there is no reason for them to feel the need to change that.
However, none of them have ever suggested that wouldn’t change in the future.
I am personally happily married and couldn’t imagine going back to being single, but I would never say that I am any happier than any of my single friends who choose to be. Happiness is subjective and what makes me happy in life may not be the same for my neighbor.
Choosing not to have a ‘romantic’ relationship does not automatically mean you are lonely. You can have hundreds of satisfying relationships with friends and family that will mean you never feel alone. If you are someone who enjoys there own space and alone time, being in a romantic relationship could actually be suffocating so remaining single is the best option.