I've got a great husband of 28 years, but I can tell you I have met several men that I could have gotten along with and married. I just look for a very kind man who is responsible with a job and is a good father. My point is..I don't think there is just one person in the world for everyone.
I know friends who prefer to be alone. They build their life around their activities and friends. If they meet someone, it is fine, but it doesn't define their self-esteem.
As for dying alone...many families are estranged and people die alone. Or people outlive their family and friends and basically die alone. Don't worry about that. I think that's out of our control a bit.