Spirituality is a need associated with religion and/or the soul. In other words, it's a need that some humans feel to bond with God, Nature, the Force, whatever you believe in. For some it must be devoid of emotion to be real and safe, for others it is not real unless it is connected with emotion. For many it is a combination of the two, an emotional and intellectual understanding of oneself and whatever one believes in.

It is something that is painful to lose, but if you have never had it, you can go through life without it and feel no sense of loss.
It is as intangible as a passing thought and as necessary for happiness to some as the emotional needs you described.
It is what many seek and never find and others know as intimately as they know their own bodies.

It is a lie that we create to make our lives and out inevitable death tolerable or the greatest of truths that gives meaning to our brief time on earth, depending on your point of view.

Faith, Hope, and Love. We all know that the greatest of these is love, but I believe that the most elusive is faith.
True faith, not the blind, ignorant belief of the masses, but a true understanding and acceptance of God or whatever else you believe guides this world is what spirituality is all about.

Spirituality in BDSM? Hmmm that would take some thinking. Spirituality separates itself from the flesh. It deals with the soul and/or the mind, and often the flesh is seen as separate, or even worse a hindrance in achieving an understanding of the spirit or God or whatever you believe in.