Major Spoiler.. Carly aka Jo is a woman Katie meets when she moves to Southport. She lives down the road from Katie's cottage. Throughout the movie Jo keeps pushing Katie towards Alex with no real explanation why. She appears to Katie in a dream once to tell Katie that Kevin, Katie's abusive husband is in Southport and that he had found her. In the end Alex gives Katie a letter from his wife, who had died of cancer before the movie started. On the envelope it says: To Her. As Katie reads she soon realizes, when she finds a photo of Alex's son Josh with his mother, the woman in the photo is Jo and that this letter was written by Jo, that Jo is Alex's dead wife. She has been watching over her family since she died and when she saw Katie talking to Alex and falling for her family she realized that Katie needed Alex just as much as he needed her. All this time this woman she thought was her good friend was his wife's spirit pushing Katie toward Alex to make sure that Alex and her kids would finally be happy again. Saddest part of the movie is when the realization hits Katie.