Eric,
Even as a believer, many people struggle with this hollow place inside that needs to be filled. Unfortunately, we often choose sin to fill the void. Especially sexual sin through deed or thought.
It makes perfect sense to me that the hollowness inside is something that has not yet been given to the Lord and I would go right along with the OP that this serious void is a lack of intimacy.
Nobody is turning this into a dirty novel, but rather looking at this in a different way. We want God to have control of every area of our life and one of the areas he created was our sexual being. It is another area that makes us part of who we are. There is nothing wrong with using a sexual analogy to help understand the intimacy a believer can have with their Creator. We use analogies all the time and just because sex is involved, it doesn't make it dirty. God created it. We've made it dirty.
Rania