Why are married couples not allowed to touch during niddah?

Question

Let me start by saying that I understand the general rules of niddah. However, I was initially very confused why the niddah period is still observed at all, even among Orthodox Jews, since the other forms of purity and impurity are no longer upheld. According to this article, Why Is Impurity Not Observed?, niddah seems to be the only purity rule that matters anymore to everyday folks.

I did find a reason why men cannot have sex with a woman in niddah.

Rabbi Avram Israel Reisner says in "Observing Niddah in Our Day: An Inquiry on the Status of Purity and the Prohibition of Sexual Activity with a Menstruant:"

With regard to sexual relations with a woman during her menses, the question to be investigated is, given that a menstruant cannot now defile non-existent sancta, is the ban on sexual relations with a menstruant still in force? Plainly, the answer to that question must be yes, for the Torah clearly prohibits cohabitation with a woman during her menses as a category of illicit sexual relations, without reference to matters of purity, in two separate verses, Vayikra 18.19 and 20.18.15

And this makes perfect sense. However, both of these verses refer just to sex.

Leviticus 18:19

Do not approach a woman to have sexual relations during the uncleanness of her monthly period.

Leviticus 20:18

If a man has sexual relations with a woman during her monthly period, he has exposed the source of her flow, and she has also uncovered it. Both of them are to be cut off from their people.

Going back to the first article:

The laws of purity are indeed technically in effect; it is just that for the most part we are presumed to be in a state of ritual impurity.

So for instance, we can touch dead people without worrying about how it affects our ritual purity (x). Why then, do we still worry about touching a woman during niddah, since the mere touch would theoretically only affect our ritual purity, not incur the penalties associated with sex with a woman in niddah? Why should a husband not touch his wife in a non-sexual manner during niddah?

Answer 1

You are right, from a strictly biblical standpoint it would seem that touching isn't a problem, other than impurity*, but this isn't an issue in our days and also isn't the reason behind the prohibition.

Our Sages can impose stringencies for various reasons, one being the concern that without stringencies people will come to transgress the biblical command.

For this reason our Sages prohibited touching a wife while being a niddah and also other actions, the details of which are discussed in Shulchan Aruch Yoreh Deah 195

A Google search about "Harchakot" will provide resources explaining this concept.

I will post some here

The shulchan aruch in YD 195:1 writes

דברים האסורין בזמן נדותה. ובו י"ז סעיפים: חייב אדם לפרוש מאשתו בימי טומאתה עד שתספור ותטבול (ואפילו שהתה זמן ארוך ולא טבלה) תמיד היא בנדתה עד שתטבול (ב"י בשם פוסקים) ולא ישחוק ולא יקל ראש עמה (אפילו בדברים) (טור וב"י בשם רשב"א מאבות דרבי נתן) שמא ירגיל לעבירה אבל מותר להתייחד עמה דכיון שבא עליה פעם א' תו לא תקיף יצריה (ל' עצמו): Matters that are prohibited during her time of menstruation, including 17 paragraphs: A person is obligated to separate from his wife during the days of her impurity until she counts and immerses (even if she waits a long time to immerse).  She is always in her Niddah status until she immerses (Beis Yosef in the name of halakhic authorities). He should not joke or engage in levity with her (even with words) (Tur and Beis Yosef in the name of the Rashba from Avot d'Rabbi Nasan) lest he become accustomed to sin. However, he is permitted to be alone with her since once he has had intercourse with her one time, his urger will no longer overcome him (his own languag

in the next Seif (195:2) the SA then discussed the actual prohibition of touching

לא יגע בה אפילו באצבע קטנה ולא יושיט מידו לידה שום דבר ולא יקבלנו מידה שמא יגע בבשרה (וכן על ידי זריקה מידו לידה או להיפך אסור) (ב"ז ס"ס קנ"ד והגהות ש"ד בשם מהר"ם): He may not touch her, even with his little finger, nor may he pass anything from his hand to her hand, nor may he accept from her hand, lest he touch her flesh (similarly, by throwing from his hand to hers or vice versa, is also prohibited).

In this lesson it is well put

This article adds a bit

Couples tend to have a certain level of familiarity, routine, and habitual rapport, therefore, the Sages - with their psychological understanding and insight - saw the need for these additional restrictions. Accordingly, these precautions only apply to married couples and does not pertain to interactions with women whom a man invariably may not touch

^{* Many of the issues caused by impurity have not been applicable for a long time, as we no longer have the service of the Holy Temple. This includes the issue of touching while Niddah, which will resume only when the Temple is rebuilt.}

Answer 2

B"H

Why are married couples not allowed to touch during niddah?

The laws of the Torah aren't only based on verses. The Torah was given together with it's explanation (Rambam, Mishneh Torah; introduction).

Hilchos isurei bia 21:1 states:

1 Whoever shares physical intimacy with one of the ariyot without actually becoming involved in sexual relations or embraces and kisses [one of them] out of desire1 and derives pleasure from the physical contact should be lashed2 according to Scriptural Law. [This is derived from Leviticus 18:30 which] states: "To refrain from performing any of these abominable practices," and [ibid.:6 which] states: "Do not draw close to reveal nakedness." Implied is that we are forbidden to draw close to acts that lead to revealing nakedness.3

א כָּל הַבָּא עַל עֶרְוָה מִן הָעֲרָיוֹת דֶּרֶךְ אֵיבָרִים אוֹ שֶׁחִבֵּק וְנִשֵּׁק דֶּרֶךְ תַּאֲוָה וְנֶהֱנָה בְּקֵרוּב בָּשָׂר הֲרֵי זֶה לוֹקֶה מִן הַתּוֹרָה. שֶׁנֶּאֱמַר (ויקרא יח ל) "לְבִלְתִּי עֲשׂוֹת מֵחֻקּוֹת הַתּוֹעֵבֹת" וְגוֹ'. וְנֶאֱמַר (ויקרא יח ו) "לֹא תִקְרְבוּ לְגַלּוֹת עֶרְוָה". כְּלוֹמַר לֹא תִּקְרְבוּ לִדְבָרִים הַמְּבִיאִין לִידֵי גִּלּוּי עֶרְוָה:

If it's without any pleasure at all, it's still forbidden, but no lashes are given, as mentioned in Ibid:6:

6 When a man embraces or kisses any of the women forbidden to him as ariyot despite the fact that his heart does not disturb him concerning the matter,14 e.g., his adult sister, his mother's sister, or the like, it is very shameful. It is forbidden15 (Nevertheless, if one has no pleasure or desire, the act is not punished by lashes [the Rambam's Commentary to the Mishnah (Sanhedrin 7:3)].) and it is foolish conduct. [This applies] even if he has no desire or pleasure at all. For one should not show closeness to a woman forbidden as an ervah at all, whether an adult or a minor, except a woman to her son and a father to his daughter.16

ו הַמְחַבֵּק אַחַת מִן הָעֲרָיוֹת שֶׁאֵין לִבּוֹ שֶׁל אָדָם נוֹקְפוֹ עֲלֵיהֶן אוֹ שֶׁנִּשֵּׁק לְאַחַת מֵהֶן כְּגוֹן אֲחוֹתוֹ הַגְּדוֹלָה וַאֲחוֹת אִמּוֹ וְכַיּוֹצֵא בָּהֶן אַף עַל פִּי שֶׁאֵין שָׁם תַּאֲוָה וְלֹא הֲנָאָה כְּלָל הֲרֵי זֶה מְגֻנֶּה בְּיוֹתֵר וְדָבָר אָסוּר הוּא וּמַעֲשֵׂה טִפְּשִׁים הוּא. שֶׁאֵין קְרֵבִין לְעֶרְוָה כְּלָל בֵּין גְּדוֹלָה בֵּין קְטַנָּה חוּץ מֵהָאֵם לִבְנָהּ וְהָאָב לְבִתּוֹ:

The same reason why it's forbidden to have relations with her is the same reason it's forbidden to touch her (during the time): because that's what the Creator decided.