Owen and Cristina have always had a complicated relationship, but then again, anything and everything with Cristina is complicated. From the start of the show, Cristina has made it clear that she mostly cares about herself and being a surgeon. Other than that, don't get in her way.
The relationship between the two has been volatile since the start, however, when Cristina decided to have an abortion, and Owen, defeated, finally agreed to it, their life began to crumble. Owen made the decision with Cristina because he knew she would do it anyway, and he wanted to be supportive to his wife. But he was and is devastated. He wanted to the baby. He wanted his wife's baby. And he can't get over it, and I don't think he should. He loved his wife and wanted a normal, healthy lifetime with her that included kids.
To be fair to Cristina, she told Owen that she did not want children, so going into a relationship and then marriage, he was aware. But accidents happen, and a lot of people are so glad when they get pregnant and change their mind. But Cristina is selfish on all levels, and she shouldn't be a mom, that most of us can agree on. However, she is so selfish, that she should also not get involved with anyone either. To be in a relationship, you have to care about the other person, which is very hard for her.
Never have fans rooted more for a relationship to end. When she thought Owen might be cheating, we knew that was not in his DNA, but part of us kind of hoped he did. He deserves someone who cares about him. We are also rooting for he and Teddy to become friends again, because that was a caring relationship and a deep friendship.
Fans will be curious to see how this plays out this spring, and who will end up staying together, Owen and Kristina, Owen and Teddy, all of them, or none of them.

