Meanwhile, Meredith and Derek's marriage becomes strained as Derek accepts an offer from the U.S. President to participate in the Brain Mapping Initiative. He receives an offer to head the project itself in Washington D.C., meaning that he would have to be based there permanently. Meredith puts her foot down as she does not want to uproot their young family to move across the country for his career at the sacrifice of her own. They begin a series of on-and-off arguments and "cold wars" over their careers. Meredith ultimately encourages Derek to go to Washington, and Derek promptly leaves. Meredith then proceeds lean on her friends for support as she begins living life as a single parent while simultaneously maintaining a streak of successful surgeries with no patient-losses. During a phone call with Derek, Meredith and Derek agree to work things out after she tells him that she did not want them to become "one of those couples" and he reciprocates, saying that he missed her. She privately admits to Alex that she has realized that she could live independently of Derek, but chooses not to.