I agree, they alluded heavily to her sleeping with the old guy, but it could be very purposeful misdirection. (spoiler for my take on what happened)

My guess is he is a caretaker or doctor of hers, and she has some crazy medical problem, and has to get regular exams or something. Though I will admit I wouldn't be surprised if she really was sleeping with him, he looked pretty relaxed with his shirt partially undone.