Right off the bat, I'm thinking that the blended family is THE most difficult family situation to have, so that is your greatest challenge. Also, the fact that this is the first relationship where you don't really argue sends a red flag that you might be avoiding issues with each other because you are afraid of conflict and "rocking the boat", so it comes out in public where you feel safer to argue (ironically?)
Like everyone else, I have my own book recommendations, but I am also one of those folks who "believes" in counseling. I convinced my hubby to go because I know that arguing in front of kids is harmful to them and I also thought "what have we got to lose by having a stronger relationship?" People told my hubby that it was "too late" once we got into couples counseling and that it just spelled d-i-v-o-r-c-e (isn't unsolicited advice just wonderfully supportive?). But I knew that we were just an outside-the-box-thinking, visionary, proactive couple who were willing to try something new to increase the quality of life for ourselves and our children. We weren't using counseling as our 'last resort' as some people do. And darn it, I wasn't going to settle for less than an AWESOME relationship that made everyone in our family happy!
Well, what do you know, it paid off way better than I even expected it to! Long story short -- he does WAY more housework and childcare now, and complains less about what I do or don't do. We are more in love than ever, and HE is HAPPIER in the relationship too, having a better relationship with our son! Make sure you get a good recommendation for a therapist -- there are a lot of crappy counselors out there -- I'd try calling a local hospital for recommendations if you don't know where to start.
BTW, the books I recommend are "Liberated Parents, Liberated Children" by Adele Faber and Elaine Mazlish -- all of their books are favorites of mine. Also, "The Relationship Cure" by John Gottman might be right up your alley.