It is an interesting derasha, and he makes a lot out of it, as a basis for a chassan having limited contact with his kallah during the engagement period. But it is based on a Maharal, rather than the gemara itself. (See the Maharal here.) The gemara states:
איש ואשה זכו שכינה ביניהן לא זכו אש אוכלתן אמר רבא והאשה עדיפא מאיש האי מצטרף והאי לא מצטרף
Now this would appear to apply to married couples, who for various reasons could have the Shechina dwelling with them, or not. But it is not clear that the issue applies to non-married couples at all, to have the problem of esh. Soncino interprets this "fire" as domestic discord, something Rabbi Falk does as well in terms of shalom bayis. But Rabbi Falk is making a diyuk from the words of the Maharal that this unmarried couple are ish and isha, and since the Shechina can only (potentially) come at the time of marriage, there is potential for eish - discord - beforehand. But in truth, we do not know that Maharal would declare the gemara to be talking at all about a case before marriage -- perhaps only when they are beyachad as one individual will the Shechina either be Sheruyah to the full extent or not, and perhaps they are not ish and isha together beforehand to yield eish. We also do not know for certain that Maharal defines esh to be discord. As we will see, it is possible that Maharal does not even say the words "when the couple marry."
Once again, here is the Maharal inside:
There are other interpretations of the gemara, such as that of Rashi, or of Ramban. Sure, if one combs all sources, one can come up with support for any idea, and kvetch the source and extend it to convey the message you want conveyed. Rashi, meanwhile, explains that zachu vs. lo zachu means that the husband, or wife, are being faithful, vs. being unfaithful, to one another. And the eish is Divine punishment for niuf. Rashi's peshat in this gemara would not support the homiletic, mussar-oriented extension necessary to prevent an engaged couple from getting to know one another better.
Indeed, one can interpret the gemara in one of two ways. The context is that this is in gemara Sotah. It this referring to the marital discord that leads to straying or an accusation of Sotah? Or is it referring to the actions of a Sotah?
Also, there is the question, even within Maharal, of what he means when he says kaasher yitchabru yachad, "when they join together." Rabbi Falk says that the Maharal says this message explicitly, but then he says he will give an approximate translation. And "when they join together" is translated approximately as "when a couple marry." The idea is that they are completing one another to form a single entity. I would note we can see this in Bereishit 2:
|כד עַל-כֵּן, יַעֲזָב-אִישׁ, אֶת-אָבִיו, וְאֶת-אִמּוֹ; וְדָבַק בְּאִשְׁתּוֹ, וְהָיוּ לְבָשָׂר אֶחָד.||24 Therefore shall a man leave his father and his mother, and shall cleave unto his wife, and they shall be one flesh.|
What does Maharal mean by yitchabru? I would indeed initially lean towards the idea that it means marriage. This is when the husband and wife become a single entity. But we see how Ramban uses the term yitchabru in discussing the very same gemara in his Igeret HaKodesh:
איגרת הקודש לרמב"ן פרק ב
אמרו חז"ל בשעה שאדם מתחבר עם אשתו בקדושה ובטהרה שכינה שרויה ביניהם. נתחממו שכינה מסתלקת מביניהם וישאר אש ואש. כדגרסינן בסוטה (יז א) היה דורש ר"ע איש ואשה זכו שכינה ביניהם, לא זכו אש אוכלתם. פי' כשהאדם מתחבר לאשתו בקדושה שכינה ביניהם, תמצא בשם האיש יו"ד ובשם האשה ה' הרי זה שמו של הקב"ה מצוי ביניהם. אבל אם לא נתכוונו לחבור קדושה אלא למלאות תאותם ומתוך התאוה והחמוד נתחממו כאש, יו"ד של שם האיש וה' של שם האשה שהוא י"ה מסתלק מביניהם ונשאר אש ואש. [והבן זה כי בכאן יש כל הסוד].
Thus, when Ramban uses the term mitchaber in discussing the very same gemara, he uses it to refer to sexual congress. And the zachu vs. not zachu refers to their intent at the time of this physical joining. (Other sources connect this with the idea of the three-fold partnership in the creation of a child -- man, woman, and Hashem.) This interpretation of the gemara, just like Rashi's interpretation, would not provide a basis for restricting conversations between an engaged couple.
This same use of yitchabru in this sense:
Of course, in other contexts, yitchabru could also mean join together, sometimes in matrimony. I think we can, with a bit of deliberation, see this in this source:תולדות יצחק בראשית פרק א
והנה בעת הזאת לא היה בין אדם ואשתו התשמיש לתאוה, אבל בעת ההולדה יתחברו ויולידו, ולכן היו האיברים כלם בעיניהם כפנים וידים ולא יתבוששו בהם, והנה אחרי אכלם מן העץ היתה בידו הבחירה, וברצונו להרע או להיטיב, עד כאן דבריו:
So let us say it does mean "join together" not in the physical sense, but in the sense of their fates being bound together. Even so, Maharal just says yitchabru, but does not specify the nature of that joining. For instance, would he consider erusin to be yitchabru? And back in the times of the gemara, erusin as betrothal was a real entity, and is somewhat akin to nowadays engagement (with the exception that at the end of a broken engagement, the woman can still marry a kohen).
תשובות הגאונים שערי צדק חלק ג שער ב סימן ט
וגדול שבאלו הדברים שכשידע הנטען שהבעל היה מגרש קדם ועשה שידוכין לפי מה שהוזכר בשאלה זו והיא עדיין אשת איש, וכל שכן שנתייחד עמה אחר אלו השידוכין הארורים, ואילו היה כזה המעשה מאלו הדרכים היה ראוי למנוע איש זה מלישא אשה זו על אחת כמה וכמה שכולם היו. הילכך מחייבין על כל פנים את האיש להפריש ממנה ומזהירין אותם שלא יתחברו בדרך נישואין קל וחומר בדרך אחר
And even if he means marriage, he is reading peshat into the gemara, such that there is possibly the Shechina sheruya in the marriage, in the joining, and possibly not. And in the case not, there is esh, whatever that means. This does not necessarily mean that absent this joining, there is a problematic aspect of the Shechina not being present.
And even if he meant that prior to marriage, there is this absence of Shechina, this not not mean that he intended his suggested explanation of an aggadic passage of Talmud to have wide-ranging impact on the practical level, of how an engaged couple should behave. And even if he did, that does not mean that we must subscribe to his interpretation of the gemara. After all, we have Rashi and Ramban's suggestions as well.
Ultimately, however, it is not going to come down to interpretations of gemaras or of Maharals, or of other sources -- even if one can clothe one's mussar in those terms. Rather, there is an overarching worldview that either sees communication between an engaged couple as something terrible, as opposed to something which is good and necessary. And I think this may be connected to the role in women in the respective societies, and the nature of the relationship between husband and wife. (This difference may have been at the root of why many people took offense at certain comments of a certain commenter, Yehuda, a while back.)
I may well be overstating this for effect, so I apologize if this is taken as stereotyping the other. In societies in which a woman is seen more as an equal, and as an intellectual being, the nature of the relationship is one of deep friendship, besides of course the physical attraction. And when the gemara in kiddushin 41a states:
it was talking about physical attraction. But as Chazal state, מה פרצופיהם שונים אף דעותיהם שונות. And with a different paradigm in our communities, the personality of one's spouse is just as important. That is why I read with horror the following, from an article in the Jewish Press.אמר רב אסור לאדם שיקדש את האשה עד שיראנה שמא יראה בה דבר מגונה ותתגנה עליו ורחמנא אמר (ויקרא יט) ואהבת לרעך
In our days, such lack of knowledge of the other person's personality can cause serious violations of veahavta lereacha kamocha. (Though this may well be clothing my own hashkafa in sources.)"I too come from a frum home (chassidish) and never associated with a male until my marriage. I actually found the idea of not really knowing my chassan until marriage thrilling. After we married we had the chance to connect in such a deep way and to talk about things I had never discussed before with anyone.The relationship exclusively between just the two of us made it so dear. I already loved telling him about myself during our sheva berachos."
The types of relationships we cultivate when dating and while engaged is one of a deep connection, hopefully where each is enamored with the other. And cutting off such a relationship as soon as engagement occurs is a bad idea. Firstly because engagement is almost like a practice marriage. (Kind of like how erusin, which was about a year before nisuin, was a marriage in which the woman still lived in her father's house.) The couple can see how they deal with various life difficulties together. And people open up in different ways once engaged. If there is some major incompatibility, it is better if this comes out at this point -- something less likely if the chassan only makes a cursory phone call to his kallah once a week. Also, the nature of the relationship they are trying to develop -- of deep friendship and love -- is not one which is bolstered by suddenly declaring that there are spiritual dangers of the couple being in each other's company, and declaring that they should only communicate minimally.
This may or may not be the exactly the same paradigm of marriage they had in previous generations. But then, for example, in Tur we find the suggestion that the optimal number of wives to have is four, so that one wife is always available. (He does not note that they should be kept apart from one another, but medically speaking, this probably necessary since women living in the same house usually find their periods converging.) But putting aside Rabbenu Gershom, could you imagine this working nowadays in our society? (Even back then, they were called tzarot.) The reason, in part, is a shifting approach to the nature of marriage, and the type of relationship and connection we are trying to foster. But I will end this here, and perhaps develop this idea in another post.