You did something illegal, which was overstaying in the country, and for that you got deported. However, that is not, by itself, grounds to refuse an application. Nevertheless, you are stating that you did not have much faith in your own application, that tells a story. With this process, the onus of proving the genuineness of the relationship is on the applicant, in this case you. If you do not do a good job, you can get your case rejected. On top of that, you did not pass the interview, which means that you did not satisfy the officer's concerns, and that was an opportunity that was given to you to explain everything and turn things around. The officers have to be completely sure that a relationship is genuine in order to approve it, otherwise they would be compromising the system, making it more vulnerable to those who commit fraud. In your case, I do not see the "unjust" that you are mentioning. Sure there are unjust cases, but I personally do not think yours is one of them, based on the little information you've shared. I can completely see, from the point of view of the immigration officer, how a decision to refuse your application would be reached.
Now note that I am not saying that your relationship is not genuine, it would be impossible to know from my end. Also, keep in mind that they should judge people's past, because it does matter, a lot. But they also judge the present, and the future. I am sure you are not being refused solely based on your past, that would be negligent and inconsistent with many other cases when people with worse pasts than yours got approved.
My point is, this can be unfortunate, unlucky, disappointing, and many other things, but unjust is not one of them. If your relationship is genuine, you have to prove it, just like everyone else, like any of us who has gone through the process and have proved we are legit. It is your responsibility, not CIC's.
