Canon is a tough argument to get into, particularly since it's constantly changed by time travel and universal law rewriting. Official is a better word for it, since their pre-Homuloop backstory is highlighted in the third drama CD, the PSP game, and The Different Story manga and is Urobuchi-approved. Granted no one pairing is actually considered "canon" apart from Hitomi x Kyosuke, Madoka's parents, and whatever's featured in the side story manga, but there's definitely more to support the ship than, say, Mami x OL.
Blasphemy! Mami x OL is the only canon ship! There's tons of evidence for it!
I still really don't get the 'Graduation might as well means the other person died' in Japan.
At my graduation, I was like 'Well... tomorrow at your place as usual?' and next to nothing changed.
From the way their talking, it sounds like the dark haired one might be moving away after graduation.
Just a question but what is it with manga like these and the need to add 'just kidding' to the end of a sweet quote? I've seen it in several of the manga I've read here today and in the past and I'm wondering why they add it.