When Brian tries to get away for awhile, they find that their moods were setting each other off, so they decide to ditch the surviving kids at an animal shelter and go back to the way things were.
When Brian tries to get away for a while, they find that Brian was only rejecting Stewie because Stewie seemed angry with him, and the cause of Stewie's anger was Brian rejecting him. After reconciling, they decide to ditch the surviving babies at an animal shelter and go back to the way things were.