In the tv show kings and queens why did carrie and doug break up?

They broke up after Doug discovered that Carrie never got rid of her Manhattan apartment and they both realized that they had different ideas about their future. They were in the process of adopting a child from China and were both racing to get there first. They ended up on the same plane and resolved their differences and picked up the baby together.Carrie finds out after adopting that she is pregnant. The show ends one year later with Doug and Carrie, and their two kids, and Arthur moving back in after a falling out with his newlywed wife.