The purpose of this study is to consider the life of Reuben, based on the Bible, who is the firstborn of Jacob and Lea from the perspective of Bowen theory, focusing on self–differentiation and triangulation. Following is the result. Although Reuben was the firstborn with competence he could not perform the role of the eldest son, committed adultery, and could not get the blessing from his father Jacob. It was known that Reuben had immature inner world because he was grown up in dysfunctional relationship with his parents. In other words Reuben kept low level of self–differentiation and got jammed in triangulation because there was emotional tension between his parents. And Reuben was both estranged from his father and fused with his mother emotionally.