That is a hallmark symptom for someone that was abused at a young age by men close to her. I think if Lee is the father, than this would be one characteristic that came as a result of that. She was unable to be close and always seemed to have a backup guy(s) because perhaps there was fear of losing someone and being with nobody. I hate to say it, but if her first real feelings in that way were with someone in the family, it would be very hard for her to duplicate in subsequent relationships when that person is still "right there". Sick, sad, but feasible.