I am not anxious about not being married ... if they only accepted married couples, then there would be no common-law status. In fact, being common-law is more restrictive and you have to submit a lot more evidence than married couples.
We lived together August 2, 2012 to August 2, 2013 in Canada when my partner came here for a working holiday visa (actually we were together longer technically speaking because when he had to leave Canada, he went to the US and we vacationed there for about a week to 10 days before he went back to his country and I went back home). We did not apply right away and this is where a lot of explanation was needed and we did actually try to explain this in our application as 1) we spent some time trying to get my partner a new work visa for the job he had left. This involved his employer of this last job in Canada applying for an LMIA first. Now he got a negative decision as his job classification was not in a category that was in "high demand". I went to see an immigration lawyer about what were our options. Family sponsorship was discussed, but at that point, we decided against it for a few reasons. We knew our red flags and weren't ready for strangers to scrutinize our relationship and my partner wanted to try and do this thing on his own first. 2) Also at that time for this country, the average processing time was 18 months, so with our red flags, probably about 2 years. We investigated other routes to come first. I stopped seeing the lawyer as it was costing us too much and not getting us anywhere fast. Ironically, for about 2 years, he decided to look into economic routes to come. When they came out with the EE program, he tried to apply there and took his IELTS twice. Meanwhile, we both had to live and make money so I went back to school and was working and taking care of my kid and then he got this crazy job where he had to work 12 hour days and 7 days a week on stretches and meanwhile trying to study for his IELTS and fill out forms for EE etc. Fast forward to 2015, we decided to look at family sponsorship again after my divorce was finalized. Meanwhile we still managed to see each other every 4-8 months on all our vacation days.
We barely qualified but apparently it is kosher enough what we submitted as they never asked us to submit more proof of cohabitation or proof of relationship. We are beneficiaries on each others' insurance plans/RRSPS for me and we have joint credit cards, Western Union receipts, we pay for each other when we were on vacations, accommodations and airplane tickets because we have been together for so long. In fact it took us a week or 2 to organize our passport stamps as we have been back and forth seeing each other for a total of about 10 or 11 times now. I had about 10 to 15 pages of this alone on my passport. The list goes on!
We are complicated but we are both really anal retentive and spent 4 - 6 months organizing our app (did the old forms then changed to new forms) including hiring a consultant to go over our app. We had to get certified translations too for our official docs.
Maybe they are wondering why we didn't get married .... we discussed this, but after being divorced ... being married is just a piece of paper to me ... if you are committed to each other, that is all that counts and the evidence speaks for itself. I understand why they want to interview us, but for some reason the exact concerns are not listed in the notes ... so hard to say what reason(s) exactly and what evidence we submitted they thought was lacking as they never asked us first to submit more proof, which we have lots of things still which they haven't seen.