My husband has always had a healthy sexual desire, but with LBD it seems to be quite enhanced. A psychiatrist suggested that this is an important way he feels connected and one of the few situations left that he can control. However, as his LBD hallucinations progressed from seeing calm people, animals, or hearing soothing sounds to much more frightening situations such as "killers" everywhere - even at home - battlefield sounds (he is a veteran also diagnosed with PTSD) - of guns/bombs/screaming, etc., creepy insects in our bed and on the floors, we needed more help to calm the visual and auditory disturbances. We were prescribed seroquel at 12.5 mg to take at bedtime. He was resistant to taking it because he also began to not trust me or anyone else in any situation. Things were fine until around day 25 of taking the medication. He was asking for sex when our grandchild was in the bed beside us or saying "I want to screw" in front of my dad and so many other inappropriate situations 24/7. He became hyper-sexual snd it became out of control. Since he didn't always recognize me, I became afraid of potential legal issues in the making if he asked the wrong person for sex. He would wake me up at all hours of the night, and many times he did not recognize me. I began to feel used, cheap, tired, and it was taking an emotional toll on me and frustrating him. Then, of course, when we did have sex, he didn't remember it later or the next day. It took a bit, but finally I realized it was the seroquel he had been taking. (It takes around 6 weeks for it to kick in.) We began to gradually decrease this medication until it was stopped, and even though it was a very low dose, stopping it has helped the situation tremendously. He still has desires but they are manageable, and easier to control. He still has a hard time remembering sexual activity but will take a "not now" or "tomorrow" much calmer. The problem is that we are back to the hallucinations, and the meds to help them in an LBD patient are very few. It is a tough situation and one that makes choices for controlling things difficult.
On a side note, at Mayo Clinic, we have repeatedly been asked in evaluations if there has been any inappropriate sexual behavior. This may be one of the side effects that is seen in disease progression. So sorry that I can't help more, but I do understand this issue. God bless you as you navigate through this long, arduous journey. I hope others have suggestions that may help. You definitely are not alone in facing this situation.