Note, that "парень" also has more specific meaning as "young man".
Approximate numbers:
мальчик (boy) = 0 to 14 years
парень (guy) = 14 to 25-29 years
мужчина (man) = 25-30 to 60 years
старик (old man) = over 60
So, if we talk about age above 30 we should say "У неё есть мужчина? Does she have a man?".