A wiser person than I once said that humans have four basic needs. One is the need to be nurtured. Next is the need to be needed. Third, the need to be noticed and finally, the need to be nudged.
Relationship is one of the most effective tools for spiritual evolution because we're always in relationships. Think of the web of relationships you have at any time – friends, parents, children, colleagues, teachers, lovers, even enemies. All are, at their heart, spiritual experiences.