It doesn't stop there. In "The Engagement," one of the questions Oswald asks Kate (during the competition between Drew and him to see who is more compatible with his girlfriend) is about how many children she wants. I can't remember if she replies one or two (she changes her answer at one point), but it sure wasn't zero. Plus, the entire episode "Kate's Family" centered on her desire to have children. She becomes so enamored with the neighbor kids that she is babysitting that she starts to think of them as her own and tries to trick them into staying with her after their mother returns. At the end, she complains to Drew about how much she wants a life with a nice, supportive guy and a couple of kids. Maybe it could be argued that this is different, because she was actually in a position of thinking she was pregnant. However, if she always wanted to have kids in the past and now has found the love of her life, why would she change her mind now? If the writers couldn't think of a more plausible reason to break up Drew and Kate than this, then maybe they shouldn't have done it.