Then they're going to be more interested in how and when you met, when you decided to get married, how much time you spent together, whether you lived in the same city for a period, etc. Lots of people provide phone bills and Skype or Gmail chat records. If you got married fairly quickly after you met, they'll probably look more closely, but getting married quickly doesn't mean there's anything illegitimate or suspect about your relationship, it just means you don't necessarily have enough documentation to satisfy your VO.
So, for newer couples - especially if you haven't spent a long time in each other's physical presence - CIC has less information because you have less information to provide when you file your application. This isn't anybody's fault, it's just reality. This means the good folks at CIC (just a hint of sarcasm here) are more likely to ask for more information from you later when they finally look at your application. One thing you can do to smooth this process is to anticipate the moment when CIC says "please provide evidence of your continuing relationship." If you keep a file to collect this documentation while your application is pending, it will be quick and easy to respond with a big pile of documentation showing you are for real. Tickets showing visits, chat logs, more photos, postal receipts from gifts you've sent each other during the wait, a receipt from a flower shop showing that one of you sent flowers to the other on a birthday or whatever - all the same stuff you submitted the first time around. The document collection process could be a nice way, for you as a young couple, to think of lots of ways to do nice things for each other, too. 8)
This applies to any aspect of your application where you struggled to put together enough information - you can anticipate CIC's next move and continue to collect documentation to reduce delays when you get a request for more information.
In my family's situation, we knew that the weak link in our application was my proof of intent to reside here because, as a Canadian citizen born outside of Canada who had never before resided in Canada, I had no ties to the city we'd chosen to move to, and only a few distant relatives in other parts of Canada. We were just fed up with the rat race in the US, wanted a change, and really liked (and now love!) Montreal. Because applications take forever to process, we weren't about to lease an apartment in 2012 for a move we expected to make 9 or 10 months later, so we really had nothing to show them other than a few emails with friends about our plans. So, after submitting our application in September 2012, during the winter and spring of 2013 before we expected the COPRs for my family, I looked for work and came up here for interviews, I opened a bank account in Canada and transferred money to it, and in May 2013 we both came to find an apartment in Montreal and we signed a lease starting in July and paid for the first month. Having the apartment lined up made it possible to know where our kids would go to school, so we could provide communications about that, too. And after that request I actually moved half of our stuff to the apartment before we got the COPRs, so I continued to collect more documentation (citizens get the same forms at customs when they move to Canada that PRs get) even after they requested more proof from us.
So, while some might consider this approach to be very OCD, the point is that if you keep in mind that there's a good likelihood that CIC might ask you for more info or documentation for any aspect of your application, you can make that moment easier and, hopefully, minimize delays if you're ready to respond quickly with a thorough stack of documents.