It's not an abusive relationship. It's SMBD, light on the SM.
I started reading them again because I really was sucked in by their relationship. I read them so fast the first time that I am noticing so many things I don't recall from reading them only two weeks or so ago.
I too did not find the relationship to be abusive, though not a role model for a healthy relationship either. But that's what makes it all the more compelling, IMHO. I think if anyone goes into this book thinking it's going to be hardcore BDSM will be disappointed. I'm gearing up for a reread myself!