Relationship is an opportunity to become increasingly open, consciously aware and loving. For some, it is a path to enlightenment. At the same time relationship can be a trap that reinforces the ego and its neuroses and causes suffering.
The difference is the degree of mindfulness and wisdom that the participants bring to the game. Without the conscious awareness that mindfulness and wisdom bring, relationship is people relating to one another through their projections and needs. When this happens, there is disappointment. When the other turns out to be whom they are instead of whom you want them to be. Disappointment leads to arguments and, depending on the health and needs of the partners, to accommodations that grow out of a need for security and unhealthy attachment, or to separation.