וַיָּבֹא֙ גַּ֣ם אֶל־רָחֵ֔ל וַיֶּאֱהַ֥ב גַּֽם־אֶת־רָחֵ֖ל מִלֵּאָ֑ה וַיַּעֲבֹ֣ד עִמּ֔וֹ ע֖וֹד שֶֽׁבַע־שָׁנִ֥ים אֲחֵרֽוֹת׃ וַיַּ֤רְא יקוק כִּֽי־שְׂנוּאָ֣ה לֵאָ֔ה וַיִּפְתַּ֖ח אֶת־רַחְמָ֑הּ וְרָחֵ֖ל עֲקָרָֽה׃
And Jacob cohabited with Rachel also; indeed, he loved Rachel more than Leah. And he served him another seven years. The LORD saw that Leah was hated and he opened her womb; but Rachel was barren.
And it was revealed before the Lord that Leah was not loved in the sight of Jakob; and He said in His Word that sons should be given her, and that Rahel should be barren.
כי שנואה לאה הנה לאה רמתה באחותה גם ביעקב כי אם נאמר שנהגה כבוד באביה שאחז בה והכניסה אליו ואל תמר בו היה לה להגיד או לרמוז כי היא לאה אף כי היתה מתנכרת כל הלילה ולפיכך לא הכירה עד שראה אותה בבקר ולכן שנאה יעקב והאלקים יודע כי להנשא אל הצדיק עשתה כן ורחם עליה וכך אמרו בבראשית רבה (עא ב) כיון שראה יעקב מעשים שרמתה לאה באחותה נתן דעתו לגרשה וכיון שפקדה הקב"ה בבנים אמר לאמן של אלו אני מגרש וזה טעם "וירא אלקים" כי חמל עליה שלא יעזבנה ויש אומרים (הרד"ק) כי שתים נשים שהאחת אהובה מאד תקרא השניה שנואה כנגדה כמו שאמר ויאהב גם את רחל מלאה לא ששנאה והיתה בושה בדבר וראה אלקים את עניה
That Leah was hated: Behold Leah tricked her sister and also Yaakov. For if we say, that she was behaving respectfully to her father who grabbed her and brought her into him and she must not cross him, then she should have said or hinted that she was Leah. Rather, she disguised herself all night and therefore, he did not recognize her until he saw her in the morning. And therefore, Yaakov hated her. But God knows that she did it in order to be married to a righteous man, and He had mercy on her. And thus they said in Bereishit Rabba (71:2) "When Yaakov saw the actions that Leah tricked her sister he intended to divorce her. And when God gave her children, he said 'shall I divorce the mother of these?'"And this is the reason "God saw" that He had pity on her that he should not leave her. And there are those who say (the Radak) that two wives were one is very beloved, the second is called "hated." As it says, " he loved Rachel more than Leah"--not that he hated her. And it was embarrassing and God saw her oppression.
כי שנואה לאה שהכיר בה אחר כך סימני עקרה כאמרו ויפתח את רחמה וחשב שבשביל זה הסכימה להטעותו:
כי שנואה לאה, because after his first meeting with her Yaakov recognised that Leah bore the symptoms of a woman who is unable to have children. Yaakov had thought that the reason Leah had been willing to deceive him was because of her awareness of her barrenness.