Some walls are hard to break down. This is one of them. I think there is fear on both your parts. Perhaps you could talk about it. Maybe a little wine would help to relax you both. I think if you could get past that hurdle things would start feeling easier. I haven't wanted to say anything. But I really think that is an important step for the two of you to take. Once things no longer feel natural together it is hard to break the ice. Don't neglect the issue. It is an important part of marriage, and probably something the two of you used to really enjoy together.