It's probably not his choice, it just hasn't happened for him
I remember having a chat like this with a girl on my course who noticed our lecturer (an old, eccentric, slightly shy type) doesnt have a ring on his finger and she said do you reckon he's gone through his life without finding a partner and quite possibly that's what happened. It doesn't mean he's any less of a person and I'm sure he's achieved things he's proud of.
Everyone is born with different talents and abilities, and things like looks, confidence with the opposite sex etc are no different - some people will naturally be attractive and others will not be that attractive. In the same way that people who struggle with basic maths or whatever will struggle to do certain jobs, people who are not particularly attractive will struggle to find a partner.
It's not for other people to patronise them or cast judgement that they are in some way 'odd' for this, remember we were all single, we were all virgins once, if other people are like this at an older age then they still deserve respect and not to be treated as freaks by other people.