I make a distinction between fictional fiction and non-fictional fiction, if you see what I mean. If there's a canon ship, then we have to work with it or go AU. There are ships that I think are reasonably indicated by subtext. So I might believe that in canon X and Y are doing it. However, since they don't exist, it really doesn't matter whether I write a story with X/Y, or X/Z, Y/Giant Squid. And if I can write an interesting story about X/B, or someone else writes wonderful Y/K/penguin, that's more than fine with me. Because what I'm going to do with a story is write it or read it, not examine it for truth value.