In the 6th (at a meal) or 7th (under the Chuppah) of Sheva Brachos, we read the line of גילה רינה, דיצה וחדווה, אהבה ואחווה, ושלום ורעות. I have heard that the first four words are referring to the relationship between a couple when the woman is Tahor and that the last four are referring to the relationship between a couple when the woman is a Niddah.
Does anyone have a source for this? I have heard that the Maharal may have said this but have come up empty locating a source.