charles barnes /ellen rouse

[jake]

hi
   can anyone please help break this brick wall down
charles barnes on 1881 census was living at 44 knutsford street balsall heath birmingham aged 28 he had a lodger ellen haydon aged 29 census say's both unmarried.
in september the same year he had a son joseph arthur, but on b/cert it say's mother ellen barnes nee rouse.so i assume he married between census date and september, i can't find marriage anywhere
  any help appreciated
                              jake