The account reveals that Hagar eventually departed from Abraham and Sarah (Gen. 21:8-21), Abraham obeying God’s command to send Hagar away. Genesis 25:6 states, however, that Abraham’s concubines’ (plural) sons were sent away, his other concubine being Susanna, as referenced in the ancient Austrian Chronicle. Abraham clearly ended these adulterous affairs. The fruit was that he removed the temptation from his life, along with the resulting illegitimate sons, in favor of cleaving to Sarah and Isaac, the son of promise.
Sarah did eventually die (Gen. 23:1-2), apparently well before Abraham. Only then did he lawfully marry Keturah (also Gen. 25). The biblical record speaks no more of polygamy in Abraham’s life.