Sforno on Genesis 29:31/ספורנו על בראשית כ״ט:ל״א

1כי 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.

2ויפתח את רחמה, Yaakov had thought that the reason Leah had been willing to deceive him was because of her awareness of her barrenness. She remained in such a state until G’d took pity on her and opened her womb.