Applying for a common law visa

[petemeen]

I arrived in Canada with my Canadian GF in January 2007.  We moved to Kelowna BC in Feb, and in March rented a condo on a 1 year lease.  In July I asked applied for an extension to my Temporay Resident Visa and asked for it to be extended until March 2009 as this would be 1 year after we had lived together continuously, and it was accepted!  My question is this, I have to return to the UK on my own and want to know how long me and my gf can be apart before we are not seen as lving together.  Any advice would be most welcome.