This really depends on the specifics of the Manager and Artist relationship. I've known managers who have remembered to buy birthday presents for their Artists' partner, have picked up their dry-cleaning, etc., etc. Likewise I've known managers who would not even be aware of whether their Artist has a partner (or has ever used a dry cleaner !!).
In general terms, their job is to be the link between the Artist and the numerous parties that need to interact with them (such as the Music Publisher, the Record Company, etc.). Often this will entail involving other specialists, rather than having to be a specialist themselves: for example, a manager would nearly always appoint a lawyer when negotiating a deal rather than handling negotiations themselves.