I suppose we'll know more by time the next story post is up, but I do want to chime in on the relationships matter.
Relationships are dangerous, because they have the potential to mean a lot of things. Those who have also hosted RDs know that there are a number of reasons why people might be paired up.
1) They're paired up by the matchmaker.
2) They share similar abilities.
3) It helps with the story (for example, in my Supernatural Doubt (which I will finish one day, I swear) I paired characters up simply because they were friends in the show).
4) For shits and gigs (to throw us off).
Obviously, number 4 is the scariest. As Shy has pointed out, we don't know his writing style. I wouldn't put it past him to pair up a killer with a non-killer. A "who the bleep did I marry" moment, where someone doesn't realize that their significant other is the killer. Besides, it could totally be possible that the matchmaker (if there is one) paired a killer and a non-killer. Assuming even for a moment that a paired person is less likely to be a killer could get us in a lot of trouble.
Also, I don't think we should assume that there is only one killer. This is a fairly large game, and most of us have encountered a RD with a secondary killer. In Dark Tower Doubt, I wrote an ability that made a person turn into a killer after a certain number of turns. The first post says that there is only one, but that could be just what we're supposed to think.
Basically, Shy is being a sneaky bastard, and I don't know what to trust.