[Another interpretation (of Genesis 39:1): "And Joseph was brought down to Egypt."] This is what Scripture says (Song of Songs 8:6): "For love is fierce as death." This is the love with which Jacob loved Rachel, as it is said (Genesis 29:18): "And Jacob loved Rachel." "Jealousy is hard as Sheol" (Song of Songs, there) — for Rachel was jealous of her sister. And what shall love do beside jealousy?
Jacob's Love for Rachel and Rachel's Jealousy of Her Sister
Midrash Tanchuma Buber, Vayeshev 19:1
[ד"א ויוסף הורד מצרימה]. זש"ה כי עזה כמות אהבה (שה"ש ח ו), אהבה שאהב יעקב לרחל, שנאמר ויאהב יעקב את רחל (בראשית כט יח) קשה כשאול קנאה (שה"ש שם), שקנאת רחל באחותה, ומה תעשה אהבה בצד קנאה.