Are an engaged couple permitted yichud or any touching (negiah)?ask your rav

There is no heter and no source whatsoever that would permit a chassan and kallah to be secluded together or to touch each other, even through clothing; he writes that he has seen many err in this. Seclusion or touching between an engaged couple is more likely to lead to worse violations than the same with any of the relatives the Torah forbids: here there is libo gas bah, he is already at ease with her, while pas besalo, which operates after the wedding, is not yet in force. Parents must know this and watch how the couple behave together, even if they are bnei Torah, for there is no guardian against forbidden relations. Whoever thinks that after the engagement everything is permitted must understand that this leads to terrible consequences. Potiphar's wife tempted Yosef for a whole year and he steadfastly refused, yet he nearly gave in on the very day when no one was at home, because that was seclusion: in yichud the fire of desire flares up so that it is almost impossible to overcome, and Yosef understood this and ran out. That is why the Sages were so strict about this prohibition. For the engagement period this is especially important: even if the chassan and kallah meet before the wedding (which is itself questionable; many Torah greats were against it), they must meet only in open places, in view of others; a meeting in a closed place may well be a violation of the prohibition of yichud.

“there is no heter — no source whatsoever to permit the chassan and kallah to be secluded”

The period between the engagement and the wedding is a time of spiritual growth for the chassan and kallah, but it must be remembered that all the restrictions of yichud and of physical contact between men and women are in full effect for an engaged couple until after the chuppah.

“all of the restrictions of yichud and physical contact between men and women are in full effect for an engaged couple until after the chuppah”

On the contrary, after the engagement these laws call for even greater care, and the couple must be extremely vigilant about yichud and negiah. The fact that they are engaged gives them no permission whatsoever to be lax or to look for leniencies.

“The fact they are engaged gives them no permission whatsoever to be lax or lenient”

The Jerusalem Talmud forbids eating matzah on erev Pesach and compares the one who does so to a man who is intimate with his betrothed while she is still in her father's house, before nisuin. The act is wrong precisely because it is premature: by the enactment of the Sages a couple does not come together before the chuppah. Rav Levi Yitzchak adds that the comparison goes deeper than a simple analogy: eating matzah is also a spiritual union, and like marriage it has its own appointed time.

He writes bitterly that nobody repents on Yom Kippur for hugging and kissing a betrothed woman while she is in the state of niddah. He therefore declared that he would not allow the tena'im to be signed until both sides undertook not to touch each other before the wedding, and that in their community a fence had been set up: the chassan does not touch the kallah and does not linger with her. Whoever crosses that fence, he writes, puts his life in danger; he spoke of this so many times that he grew hoarse from shouting.

“for crossing over it is life threatening”

At a private audience the Rebbe told Reb Uriel Zimmer that he was deeply pained by the conduct of chassanim and kallos during the engagement period; among other things, they not infrequently violate the prohibition of yichud. The Rebbe said he was looking for a solution but believed a public campaign would not help here.

“he was deeply pained by the conduct of chassanim and kallos during the engagement period”