Spirituality can be seen in virtually anything in our lives. Part of being grounded and living life to its fullest is to enjoy and appreciate life and human contact. We are blessed to love and share an intimacy that was meant for pro-creation and our survival as a species on earth. The act of sex can be seen as creating an energy, just like running, jogging or biking, but the difference is that there is a release of this energy, releasing hormones and endorphines or feel good chemicals into our body.
That being said, there are also practices of something called
"sex magick", which is basically using your intent or focusing that energy towards a desired goal or outcome. If you are interested in reading more about this please see also
Its interesting reading if nothing else.