"Having each other" is a phrase that suggests people are connected, acquainted, or companions. Therefore, the antonyms for this phrase could be "separated," "divorced," "estranged," or "disconnected." These words signify a lack of connection, commonality, or rapport between people. The opposite of having each other is having nobody, hence, "lonely," "isolated," or "abandoned" are also antonyms for this phrase. In contrast, "coexisting," "collaborating," "bonding," or "united" could be related terms for "having each other," denoting various forms of harmony, cooperation, or cohesion among individuals.