I have been with my fiance for four years, we have a beautiful healthy 19 month old boy. For some reason during sex I have to picture other men.. I love my sons father and he's perfect for me. I do have PTSD due to sexual abuse so I'm not sure if that's related but I would like to be able to be satisified with just having regular thinking about each other sex. I feel ashamed. -_- any tips of advice?