There are things we stay away from as sin, that if we knew our own hearts and human intimacy, we would flee from out of knowledge instead

People imagine to themselves that they know their own hearts, and that they understand sexual intimacy, simply because they are capable of participating in it.
This is not true. I remember people I met who had been divorced because they had engaged in the practice of swapping spouses for a night of intimacy. If you asked them “do you know your own heart”, surely they would have answered “yes”. If you asked them, “do you understand sexual intimacy” they would have been indignant at the suggestion that they did not.

But they did not know either. If they knew their own hearts, and understood sexual intimacy, then when someone had suggested they swap spouses for a night of intimacy, quite independent of whether it was sinful, they could have considered, and known in advance that to do so would have such profound effects upon them that they would end their marriage over the consequences of that single night.

We don’t know our own hearts. We need to come to God, and learn to relish the joy and freedom of the gospel, and begin to have the Holy Ghost in some measure come into our lives, and help our hearts to become hearts of flesh instead of hearts of stone. The more we can do this, the more we will know our own hearts.

I honestly don’t believe there is a living soul that understands human intimacy. We only know that it is a source of tremendous joy. It is the peculiar soul of marriage.