For that question, list every time you have stayed together. Even for short periods, such as the honeymoon. It may seem CIC means cohabitation as the 'one year' needed for common law, but if you read immigration appeals, you will see that the Immigration Appeal Board members hearing the cases expect even short periods of staying together to be mentioned. I saw one case where the judge found that the couple was lying because in one place they said they had gone on a honeymoon, but for this question about living together they had answered 'no'.
Explain the situation clearly. This way, even if the visa officer does not consider whatever time you spent together to be cohabitation, he or she will not think you are lying.
For example: We stayed together for three weeks at Hotel X in ___ for our honeymoon, from (date) to (date).
We stayed together in his apartment for three months when I went to visit him in Austria from (date) to (date).
We stayed together for two weeks at Hotel X in ____ on a vacation, from (date) to (date).
And so on. Then include evidence of this - hotel receipts, flight tickets and boarding passes, letters from roommates or friends mentioning the stay, whatever you have.
If you decide to answer 'no' to this question, at least explain: "We have not lived together as a couple for a year or more, but we have stayed together for shorter periods on visits, vacations, and our honeymoon. The details about these visits can be found ____. (That is, make sure they are mentioned somewhere in the application; there is a question about the honeymoon; you could also talk about such visits in the letter where CIC asks for further details about the relationship.)
