My husband and I are in the same situation. We live 4 1/2 hours apart and we cross the border every weekend and have been together since 2012. For that question, and the corresponding one of how many times I visited him in the states, we explained our situation - how often we see each other, the routine we have (leave after work on friday, arrive by 9pm, go home sunday) and totalled up all the days each of us had visited up to the day the application was sent away. We wrote that most weekends are spent at home watching movies and ordering pizza, but any important details for visits were listed on the attached pages.
On attached typed up pages we listed the actual dates of every visit we've made to each other, broken up into times he'd visited me and times I've visited him. I'm sure they expect a plane ride every six months or something for most couples, but even though our list of dates is longer doesn't mean we don't have to answer the question all the way, was our feeling. We listed the year as a header for each 12 months, then the month and days. Ie., 2012: July - 13, 14, 15th, etc.
On the last page we listed the details for all the important dates. Ie., On June 16th 2013 I met my husband's kids for the first time at his son's soccer tournament in Webster, NY. On May 31st 2013, He was in Kitchener by 9pm and proposed to me that weekend. On August 17th 2013 we took the kid's to Canada's Wonderland. On Oct 14 and 15th 2013 we were in Niagara on the Lake for our honeymoon.
We made a note to refer to the proof of relationship folder and in there we included all our bank and visa statements and highlighted all the purchases made over the border to correspond to the dates listed. There were some other proofs as well, like our tattoo appointment card, Canada's Wonderland tickets and other receipts showing things we'd bought during our honeymoon. In the end we have like 200 dates listed and a whole page of important activities and events, but it was a fully answered question haha! Hope that helps
