This is all but a part of Ben's master plan. Ben has to get Sun to think that Jin is dead when he is actually not but alive on the island with Michael. Remember Ben says to Jack at the funeral home that he could get them all to go back. Of course Ben adds that this is a theory and has many ideas on how to do this but how? Ben as we know needs Jack, Kate, Aaron, Sun, Locke's body, and Sayid to go back. Does this include Widmore? I think that she may go help Widmore but it is a part of Ben's plan to make Sun angry to get her to do what he wants.