On the never-ending list of bugs on Aela's page on the Elder Scrolls wiki there is one that says:

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

SRSLY. Check it out if you don't believe me. XD Pretty self-explanatory. DB attends his/her wedding ceremony and is confused/shocked/angry/whatever that Vilkas is there instead of Aela. I'd like this to be a humorous piece.