The love between Jacob and Rachel was love at first sight. This is revealed love: Rachel is “beautiful of form and beautiful of appearance”, and Jacob connects to her in the revealed part of his soul, what he knows and recognizes. In the language of Kabbalah, Rachel represents the sefirah of malchut, kingdom, the revealed world. (Alma d’itgalyah).
As opposed to Rachel, Jacob receives Leah unknowingly. “And it was in the morning, and behold, she is Leah.” It is not written that Jacob loves Leah. She feels “hated” in comparison to her sister, Rachel. Nevertheless, it is specifically from Leah that most of the tribes are born, among them the tribe of priesthood (Levi) and of kingdom (Yehudah).
In truth, the connection between Jacob and Leah is very deep – so much so that Jacob himself is not aware of it in the beginning. Leah is the internal, concealed world (Alma d’itkasyah) and she is the soul-mate of the internal, concealed portion of Jacob. Moreover, according to Kabbalah, the main part of the connection is between Yisrael and Leah, the name that was added to Jacob that expresses his lofty level. Jacob did not think that Leah was his soulmate. But Yisrael loves Leah very much.