Board Thread:Skyrim/@comment-11441888-20130715195118/@comment-6881629-20130715201043

The wiki page says -

"When walking into a wedding with Aela, Vilkas may be waiting at the altar instead"

Not relevant but i found it odd... Try going to Maramal and getting a new amulet apparently some of them don't work (also you may have to talk to him about marriage before the option will appear).