The Torah commands in Parashat Emor (Vayikra 21:13) that a Kohen Gadol must marry specifically a Betula (virgin). This Misva is listed as one of the Torah’s 248 Biblical commands.
The Sefer Ha’hinuch explains that a person must ensure that his thoughts are pure, because improper thoughts lead to improper conduct. Therefore, the Kohen Gadol, the closest servant of G-d in the Bet Ha’mikdash, must maintain the strictest standards of thoughts – and this is true of his wife, as well. He must marry a woman whose thoughts are exclusively on him, and not on any other man. A woman who is not a Betula, even if her prior relationships were permissible, is considered unfit for the Kohen Gadol, because she had strong feelings for other men which might still linger, and this would compromise the sanctity of the Kohen Gadol. Moreover, the Sefer Ha’hinuch writes, this would have an effect on the offspring they produce. Marrying a Betula helps ensure the sanctity of the union and of the offspring.
The Sefer Ha’hinuch acknowledges that even a Betula may have had feelings for another man. However, he explains, these feelings are not strong enough to disqualify her for marriage to a Kohen Gadol as long as she never acted upon them and had a physical relationship. It is only if she had such a relationship that her feelings for that other man could compromise the sanctity of her marriage to a Kohen Gadol.
One might question the Sefer Ha’hinuch’s explanation in light of the Gemara’s ruling in Masechet Yebamot (59) that once a girl becomes a Halachic adult (at age 12), called a “Bogeret,” she is forbidden for a Kohen Gadol despite never having had a physical relationship with a man. Why should she be forbidden for a Kohen Gadol, the Sefer Ha’hinuch asks, if she has never had a physical relationship? The Sefer Ha’hinuch answers that at this stage, even if a woman is a Betula, her Yeser Ha’ra (sinful inclination) is especially strong, and she may likely have feelings towards a different man even if she had not a relationship with him. Reaching Halachic adulthood is thus considered akin to having had a relationship. It is only when she is younger that specifically a relationship will result in lingering feelings towards someone, thus disqualifying her for marrying a Kohen Gadol.
The Sefer Ha’hinuch also addresses in this context the situation of “Nit’almana Min Ha’erusin” – if a girl was Halachically betrothed to someone who then died before they married. Even though the girl is still physically a Betula, nevertheless, she may not marry a Kohen Gadol. The Sefer Ha’hinuch explains that the betrothal creates strong feelings toward that man, and so the girl is forbidden to marry a Kohen Gadol.
It emerges, then, that before Halachic adulthood, a physical relationship or betrothal disqualifies a girl for marriage to a Kohen Gadol, and upon reaching adulthood, she is disqualified even without having been betrothed or having had a relationship.
A woman who had a relationship with a man “She’lo Ke’darkah” (not in the usual manner of intercourse) may not marry a Kohen Gadol, even though she is physically still a Betula. The Sefer Ha’hinuch explains that such an encounter creates feelings for the man, and thus disqualifies the woman for marriage to a Kohen Gadol.
This prohibition applies also to a Mukat Etz – a woman who suffered an injury that resulted in her no longer physically being a Betula. Although she did not have a physical relationship with a man, she nevertheless may not marry a Kohen Gadol. The Sefer Ha’hinuch explains that a woman feels a special bond with the man because of whom she is no longer a Betula. Therefore, if she lost her “Betulim” through some other means – even if this did not occur during an intimate relationship – this would compromise somewhat the closeness of her bond with her husband.
These laws apply to all Kohanim Gedolim – those who were consecrated with the special Shemen Ha’mish’ha (anointing oi), and those who were consecrated by putting on the special priestly garments. They apply even to a Kohen Gadol who served as a temporary substitute for the Kohen Gadol, and is no longer a Kohen Gadol. They are also relevant to a Kohen Mashuah Milhama – the Kohen appointed to accompany the soldiers when they go out to battle.
As mentioned, a woman who was betrothed may not then marry a Kohen Gadol even if the groom died before they could get married.
If a Kohen Gadol betrothed a girl and she became a “Bogeret” before the wedding, he should not then marry her.
A Kohen Gadol may not marry two women.
If a regular Kohen was married when he was appointed Kohen Gadol, he may remain married to his wife. Even if he had only betrothed a woman before his appointment as Kohen Gadol, he may marry the bride after being named Kohen Gadol, since she was permissible to him at the time of the betrothal.
This prohibition obviously applies only in the times of the Bet Ha’mikdash, when there were Kohanim Gedolim.
A Kohen Gadol who married a woman who was not a Betula would be in violation of this affirmative command, and would be required to immediately divorce the woman.
The Mishna in Pirkeh Abot (5:21) teaches, “Ben Shemona Esreh Le’hupa” – that already at the age of eighteen, one should get married. Some found an allusion to this teaching in the verse which commands a Kohen Gadol to marry a Betula: “Ve’hu Isha Bi’btuleha Yikah.” The word “Ve’hu” in Gematria equals 18, such that this verse may read to mean, “At 18, one should marry a Betula.”