ok...well I"m not sure where the "Canon" comes in but yes James and Victoira were mates in Twilight,,,,but then the Cullens killed James which is why Victoria tried to kill Bella with the newborn army in Eclipse.
The canon part comes from Fanfiction... it means that the couple in fanfiction are the same as they were in the books... Anoter canon couple would be Alice & Jasper, but a non-canon would be say, Rosalie & Carlisle