Or HaChaim on Genesis 29:30/אור החיים על בראשית כ״ט:ל׳

1 ויבא גם אל רחל. He also slept with Rachel. The reason that the word גם, also, appears twice in this verse maybe to indicate that Jacob spent more time with Rachel than with Leah. According to Bereshit Rabbah 98,4 Jacob's bed was usually besides that of Rachel. The Torah states not only that Jacob spent more time with Rachel but that he also loved her better than Leah. This was unnatural inasmuch as familiarity usually leads to a lessening of the bonds of love. We know this from Proverbs 25,17 where Solomon advises "visit your neighbour's house sparingly, otherwise he will become fed up with you." On the other hand, we are familiar with the proverb that "absence makes the heart grow fonder." This is what is meant when Proverbs 9,17 describes "stolen waters as especially sweet." In Jacob's relationship with Rachel and Leah respectively, these psychologically sound rules did not apply. All of this is alluded to in the repeated use of the word גם.