Why do some of us end up alone? Is it just fate?

I do the right thing. I work, I take care of my elderly neighbors. I lived with and took care of my grandmother who was legally blind for 3 years before she died at age 92. I have a good job that required 8 years of training. I don't harm people. I provide volunteer medical care in Africa. I've been looking for a real relationship since I was in my 20s.

I really thought that if I did the right thing, I'd find someone. Not that it would be some sort of reward provided by fate, just that it would work out for me the same way that it worked out for all of the people around me. We'd have a good relationship and have kids. I'd have a family and a purpose.

At this point, I realize that I need to come to terms with the fact that none of that is going to happen. I'm old.