I visited my wife on our anniversary and had the same question. I emailed LVO and this is the response they gave me:I would advise you to keep them and submit them when the visa office ask for additional documents.
Dear Applicant,
Please be advised that we encourage you to send us documentation as evidence of your continued relationship with your spouse.
Yours Sincerely,
NXR
High Commission of Canada
Immigration and Medical Services Division
Canada House
Trafalgar Square
London
SW1Y 5BJ
United Kingdom