An excellent way to close discussion of a complaint is to focus on what the two of you can do to make things better. Perhaps this is the time to say, "My new job is really important to me, but our relationship is much more important. Maybe we can set aside special times each week when we will keep outside concerns from intruding on our time together."
Sometimes people agree to make things better but neglect to discuss concrete changes that will resolve what triggered the complaint. Taking the time to identify and agree on specific changes is crucial.