How to Do It I thought we’d be done with this by now. Photo illustration by Slate. Photo by airdone/iStock/Getty Images Plus.  How to Do It is Slate’s sex advice column.  Have a question?  Send it to Stoya and Rich here.  It’s anonymous! Dear How to Do It, My husband and I have been married for 42 years since I was 20 and he was 24. We have four amazing adult children and seven grandchildren. My husband and I have only had intercourse with each other. I have always been a very modest person, and I still am to a certain extent. He absolutely is not. Obviously, neither of us looks the same as we did when we first met. My husband is always saying how amazing I look and compliments me a lot. Over the past five years, we really haven’t had much sex since he is diabetic and is not able to perform. I have never really cared about sex. It was good when we had it, but I didn’t need it. He always wanted it. Lately, he has been wanting me to tie him up and be mean and controlling.…