Shalom and thank you for your question! The commentaries indeed discuss this important issue, of how the Patriarch Jacob could marry two sisters, which is forbidden by the Torah. Bigamy is not the issue, since the Torah does allow more than one wife. Over a thousand years ago in Europe, the great Rabbeinu Gershom made a Rabbinical decree forbidding marriage to more than one woman, having experienced first hand danger to his life when his younger wife, (whom he had married at his older wife’s request, in order to have children, since the older wife was barren,) became an accomplice to an antisemitic defamation scheme against him. The decree expired in recent years, but Ashkenazic authorities do not plan to revert to the previous situation where more than one wife is acceptable, as far as I know to date. There are cases in Israel of Jews from countries such as Yemen, (where it was legal to marry more than one wife, according to both secular and Jewish law,) who made Aliyah with multiple wives, but otherwise it is not the practice today.
Returning to Jacob… His original intention of course, was to marry Rachel, knowing that she was the wife that was intended for him. Laban however, after letting him work hard for seven years, cheated him and dressed Leah as the bride. Commentaries say that Leah was the older identical twin, and thus Jacob did not perceive the deception until the morning after the wedding night. Rachel had compassion on her sister, and gave her the secret code that had been arranged between Jacob and herself, in order to spare Leah intense embarrassment. (For which she was rewarded by G-d who accepted her prayers for the Jews as opposed to the prayers of other Jewish leaders, and she was promised that the Jewish people would return to their borders.)
Various commentaries explain that the fact that the Patriarchs kept the entire Torah was what is called in Jewish law, a ‘hiddur’, a beautification of the commandments, which is optional. Therefore Jacob had three options on that fateful ‘morning after.’ Divorce Leah, on the legitimate grounds that he had been cheated, and then marry Rachel as planned, or stay with Leah and apologize to Rachel that he had not done it intentionally, or – take the lenient Halachic (Jewish legal) view that since he was keeping the commandments before the giving of the Torah only as a hiddur, a voluntary act, he could stay with Leah and take Rachel as well.
There are opinions that keeping the commandments for the Patriarchs was voluntary only outside of Israel, and therefore Rachel was destined to die just before Jacob’s return to Israel, when giving birth to Benjamin.
The Lubavitcher Rebbe goes to great lengths to emphasize that the course of action that Jacob chose, the third option of staying with Leah and marrying Rachel in addition, was, bottom line, a matter of keeping his word!
Jacob had given his word to Rachel, she had waited seven long years, (and would have probably been offered as a wife to the wicked Esau,) and he wasn’t going to disgrace Leah, who was a pawn of the wicked Laban.
In short, explains the Rebbe, there are times when the lenient approach must be taken, to do what is humanly right. Jacob had promised, he must come through with his promise
- S. The Rebbe’s talk on the above subject is in volume 5 of the Rebbe’s talks.
הרחבה בענין זה ניתן למצוא בסידרת לקוטי שיחות כרך ה’, שם גם מובא ההסברים השונים ההלכתיים של ענין זה
