What they said. Plus, that's where fanon, fanfictions and headcanons come into play: there might have been some instances in canon where the ship was evident, and if said ship's fans like them, then why can't they have a secret fiction of their own, if they feel good with it? Hope you understand :)
Shipping has nothing to do with whether people ship two characters together. That's whether the ship is canon or not, the way the actual characters feel have nothing to do with it.
Yeah, this is the main reason I don't ship it. I don't think they had any romantic tension like Ron & Hermione or even Harry and Ginny (I'm not a Hinny shipper). But no hate towards the people that like it.