In Integral Relationships: A Manual for Men, "soul" is defined as the unique/authentic sense of self that remains after we strip away all learned conceptions and false beliefs (ego) about who we are (page 58). This is best accomplished in authentic soul mate relationships.
In first-tier "need-based" relationships, the term "soul mate" is often (mis)used to describe a partner who triggers a rush of love hormones by fulfilling our primary fantasy, sharing of mutually compatible pathologies, and making us happy by meeting our various needs. As partners grow through the stages of first-tier consciousness, their material and psychological needs change. Unless they manage to heal and evolve together as a couple, who they perceive as their "soul mate" changes as well.
Scott Andrews with www.AspireNow.com offers us five ways to spot lifelong soul mates who are in Integral relationships (see end note #222 in Integral Relationships: A Manual for Men for complete text):
1. They contribute more good to the world as a team than if they were apart.
2. They are both aware of their spiritual nature. They have their eyes first upon a higher evolutionary calling or power, second upon each other, and third upon their purpose together. Their family, career, and other things will always follow in some priority after these three.
3. They are on an evolutionary spiritual life journey. These journeys, when their souls coincide for maximum impact, always run parallel in such a way that it creates a relationship that is more about the union, or the team, than the individual.
4. They offer unconditional Love (that does not want anything) to each other and challenge each other to learn the lessons that support their awakening process (John Welwood calls second-tier soul mates "worthy opponents").
5. They possess harmonious and complementary natures. Their relationship is about who they are (experiences) and what they contribute to better the world, rather than what they have (possessions/social status).
Integral Relationships: A Manual for Men provides you with a clear vision and road map how to co-create a second-tier soul mate relationship with an opposite and equal partner.