When he youngest of three sisters, depending on her boyfriend for happiness, crosses the Atlantic Ocean to say good-bye to her estranged father before he dies, she must confront and finally put an end to the painful patterns of her childhood that have affected all her relationships.

"An over-reliant romantic must independently see her dying father one last time all whilst confronting the resurrecting demons of her long forgotten childhood."

Sorry if my attempt at condensing your logline doesn't quite line up with your story since I honestly had trouble understanding the intricacies of said story. For clarity's sake try to omit details such as, "the youngest of three sisters," and "cross[ing] the Atlantic Occean," since these come off as unnecessary given they don't seem to have all that much significance, ay least as far as the logline alone goes.