Ralph had told Isabel long ago that if she wanted to see the ghosts in Gardencourt, she must suffer greatly. During the night she senses the presence of something and upon leaving her room, learns that Ralph has just died.
Isabel remains at Gardencourt for a while so as to comfort her aunt and to recover her own strength. One day she receives two visitors. The first is Lord Warburton who again extends to her an invitation to visit his home. The second visitor is Caspar Goodwood. He tries to make Isabel see that it is foolish for her to return to her husband. He tells her that he knows everything and can see no reason for her to return to "that ghastly form" of a marriage. He tells Isabel that the world is wide and there are many places where they could live. "She had wanted help, and here was help; it had come in a rushing torrent." Goodwood takes her into his arms, and "his kiss was like white lightning, a flash that spread, and spread again, and stayed Isabel recovered herself and realized that her path was now very straight.
Two days later, Goodwood calls at Henrietta Stackpole's in London and learns that Isabel has left that morning for Rome.
Why Isabel decides to return to Gilbert Osmond must be finally determined by each individual reader. There could be many reasons. Isabel is proud, and in her pride she cannot stand to admit her mistake to the entire world. As she told Henrietta, she cannot publish her error for the whole world to see. Furthermore, Isabel puts great emphasis on her promises. She had undertaken certain marriage vows and she cannot bring herself to break them. Likewise, she had promised Pansy Osmond to return. And finally, in her interview with Caspar Goodwood, Isabel sees the danger she would face if she does not go back. In this final scene, Isabel is afraid that if she does not return she would compromise herself and thus would be no better than Madame Merle or the Countess Gemini. In other words -given Isabel's nature-the only course open to her is to rejoin her husband.