Why is there a time of physical separation between husband and wife every month – a law found in this week’s Torah portion?
Perhaps the separation points to a difference between Jewish and fundamentalist Christian approaches to sexuality. In Christianity the basic purpose of sex is procreation. In Judaism, as important as procreation may be, marital pleasure as an expression of deep love is even more important. Note the words of Ramban: “Speak words which arouse her to passion, union, love, desire and eros” (Epistle of Holiness). Of course, such words and actions should be reciprocated by wife to husband.
It may be suggested that a time frame of separation is mandated to heighten the physical encounter. A kind of pause that refreshes, allowing for the love encounter between husband and wife to be more wholesome, more beautiful.
Rambam in his commentary to the Mishnah (Avot 1:16) wrote about love between husband and wife as empathetic friendship, a camaraderie involving a caring responsiveness, a sharing of innermost feelings – a relationship of emotional rapport rooted in faith and confidence.
Here again, a time frame of separation may be mandated to make sure that spouses can relate in ways other than physical, and then transfer those feelings to the physical realm when permitted.
One last approach. In many ways love is not only holding on, but also letting go. To be sure, love involves embracing the other, but in the same breath it allows the other to realize his or her potential. This is the great challenge of harmonization. How can I be one with you while letting you be who you are? On the other hand, how can you be who you are without our becoming distant and alienated from each other?
This could be the meaning of ezer k’negdo (Genesis 2:18), which Rav Yosef Dov Soloveitchik understands as Adam’s “discovery of a companion who even though as unique and singular as he, will master the art of communicating and with him form a community.” (Lonely Man of Faith, p.26)
Therefore a time frame of separation is mandated to foster individuality even as the coming together fosters commonalty. Each is stressed in the hope that it will spill over and become part of the other and forge a balance.
These rationales do not explain why the separation takes place at the time of niddah or why immersion in a mikveh is crucial for purification, but they may offer some understanding of why the Torah sees the separation as a conduit to enhancing love between husband and wife.