Yeah--assumption #3 bugs me, because the truth is, before we met Tonks, I was happily assuming that Remus was mostly going to be a solitary guy, maybe ending up headmaster, still living alone and more or less happy that way. He didn't seem right in a romance. Then Tonks came along as a character and just seemed to click.

As to #1... why would we hate Sirius? That's just stupid. Both Tonks and Remus love Sirius. Why would someone who likes both Tonks and Remus hate him?