I'll start by outlining the kinds of social problems your husband or wife, or boyfriend or girlfriend might have, and the many factors that can influence how it will all play out.
Next I'll give some suggestions about what you can do about it.
I think this site is a detailed resource on the social struggles people can go through, and how they can think about them.
Everyone is different, so going through general information may not give you insight into every little thing your partner does or is going through, but it should help.
If they work at it they can build up their communication skills or become less shy and insecure.