Genesis 32:24-30 describes the conversion of Jacob. Chapter 35 verses 2 through 4 describe his coming out of idolatry after God changed his name to ISRAEL. This new name meant “overcomer” or “prince of God—prevailer with God.” In time, God permitted Rachel to die (35:19), and Jacob remained faithful to his original and only real wife, Leah, for the rest of his life.
All people must turn from every form of sin, and polygamy was simply a sin like any other from which Jacob had to turn.