Relationships can take many forms, and the crossword solutions provide a few examples. A PLATONIC relationship is one that is purely based on friendship and does not involve any romantic or sexual feelings. A causal relationship is one that is based on convenience and does not involve any emotional attachment. An OPEN relationship is one in which both partners are allowed to have other relationships outside of the primary one. A SPATIAL relationship is one that is based on physical proximity, such as between neighbors. A same-sex relationship is one between two people of the same gender. A long-term relationship is one that has been ongoing for a significant amount of time. An on-and-off relationship is one that has periods of being together and apart.