1) ONE WHO IS CHILDLESS OUTSIDE OF ISRAEL
QUESTION: The Mishnah and Beraisa state that if a couple has been married for ten years and has had no children, the man should divorce his wife and marry another woman in order to fulfill the Mitzvah of Piryah v'Rivyah. The Gemara derives this time span from Avraham Avinu, who married a second wife after ten years of childlessness. The Gemara adds that Avraham Avinu married his second wife ten years after he arrived in Eretz Yisrael; he was actually married to Sarah for more than ten years when he married a second wife. The Gemara says that the years he lived outside of Eretz Yisrael are not counted, because perhaps it was the lack of merit of Chutz la'Aretz that caused Avraham Avinu not to have children.
Does the Gemara imply that one who lives in Chutz la'Aretz may not divorce his wife if they do not have children for ten years, and that they may assume that it is the lack of merit of Chutz la'Aretz that prevents them from having children? Why should they be permitted to assume that it is the lack of merit of Chutz la'Aretz which causes them to be childless, when many people who live in Chutz la'Aretz do have children?
ANSWERS:
(a) The RASHBA cites RASHI (Bereishis 16:3) who explains that the reason why Avraham Avinu had to wait ten years after his arrival in Eretz Yisrael was that Hash-m promised him, "I will make you a great nation," only after he fulfilled the commandment to go to Eretz Yisrael ("Lech Lecha..."). Hence, it was only Avraham Avinu for whom the years of living in Chutz la'Aretz did not count. Avraham Avinu was unable to have children, and Hash-m promised him that his physical nature would change and he would have children only after his arrival in Eretz Yisrael. Accordingly, there was no point in counting the years during which he lived in Chutz la'Aretz; those years did not count because he was physically unable to have children there and not because of the lack of merit of Chutz la'Aretz.
(b) The ROSH (6:12) explains that Avraham was in Eretz Yisrael at the time of the Bris Bein ha'Besarim, when he was 70 years old (Rashi, Shemos 12:40). However, at the time he moved to Eretz Yisrael with his family, he was 75 years old (Rashi, Bereishis 12:4). Why did he travel to Eretz Yisrael when he was 75 if he was already there when he was 70? The answer is that Avraham made a "pilot trip" to Eretz Yisrael at age 70, without the rest of his family. Five years later he returned with his family in fulfillment of Hash-m's command to him. Accordingly, the reason why Avraham Avinu did not merit to have a child in Chutz la'Aretz was because he delayed the fulfillment of Hash-m's command for five years. All others have no specific command to leave Chutz la'Aretz, and thus the years they live in Chutz la'Aretz do count towards the ten years of marriage with no children.
The ROSH and RA'AVAD (cited by the RASHBA) add that following his first trip, Avraham Avinu left Eretz Yisrael to return to Chutz la'Aretz. Leaving Eretz Yisrael to go to Chutz la'Aretz is considered a misdeed which can cause a person to lose the merit to have children. For this reason, Avraham Avinu did not count the years that he lived in Chutz la'Aretz towards the ten years of marriage with no children. In contrast, one who always lived in Chutz la'Aretz and never left Eretz Yisrael to go there is not held accountable and does count the years that he lives childless in Chutz la'Aretz.
(c) The RAMBAN explains that perhaps a person is required to divorce and remarry after ten years in Chutz la'Aretz. However, if he goes to Eretz Yisrael after ten years the count starts anew; perhaps the merit of Eretz Yisrael will enable him to have children (and not that the sin of living in Chutz la'Aretz prevents him from having children).
(d) The HAGAHOS MAIMONIYOS (Hilchos Ishus 15:4) cites other Rishonim (Tosfos, Semag, Ra'avyah) who indeed rule that a man in Chutz la'Aretz cannot be forced to divorce his wife after ten years of childlessness, because it might be the lack of merit of Chutz la'Aretz that prevents him from having children (and thus it will not help to marry another wife). RASHI (DH Miketz) also implies that this Halachah applies to anyone who lives in Chutz la'Aretz. (For a summary of the Halachah in practice today, see following Insight.)

64b----------------------------------------64b

2) HALACHAH: DIVORCE AFTER TEN YEARS OF CHILDLESSNESS
OPINIONS: The Gemara concludes that even nowadays the law of the Mishnah remains in effect. If a couple has been married for ten years and has had no children, the man should divorce his wife and marry another woman in order to fulfill the Mitzvah of Piryah v'Rivyah.
Does this Halachah require that Beis Din force a man to divorce his wife after ten years of childlessness, or is it merely an obligation upon the husband himself to take the initiative to divorce his wife on his own accord, and Beis Din does not get involved? This question is the subject of debate among the Amora'im in Kesuvos (77a) and is also the topic of discussion among the Rishonim here.
(a) RASHI (65b, DH Hu and DH Hi) writes that Beis Din must force a man to divorce his wife (and marry someone else) in order to have him fulfill the Mitzvah of Piryah v'Rivyah. This is also the ruling of the RIF and the RAMBAM (Hilchos Ishus 15:7) who write that Beis Din compels him to divorce her even if Beis Din must use physical force. (The ROSH (6:15-16) adds that Beis Din also forces him to marry another wife, because otherwise there would be no point in forcing him to divorce the first one. Similarly, Beis Din is enjoined to force, at a certain point, a bachelor who refuses to get married.)
(b) TOSFOS (DH Yotzi) and RABEINU CHANANEL rule, based on the YERUSHALMI (Kesuvos 11:7), that Beis Din does not force the man to divorce his wife. Rather, Beis Din tells him that he is obligated to divorce his wife and that if he does not, the people will be permitted to call him a sinner.
HALACHAH:
(a) Who exactly does the Gemara require to divorce his wife and marry another woman after ten years of childlessness?
1. The Poskim cite the Yerushalmi which states that the Gemara's ruling applies not only to one who had no children or who had stillborns, but even to one who had children but they died and he no longer has any living children (or grandchildren). He, too, must divorce his wife if ten years have passed and they have not had more children.
2. The Mishnah states that this Halachah applies when ten years pass "without giving birth." The RAMBAN and other Rishonim infer from these words that if a man's wife bore him a single child, he is not required to divorce her, even though he has not fulfilled the Mitzvah of Piryah v'Rivyah with the birth of a single child. The REMA records this ruling as the Halachah in practice. The PISCHEI TESHUVAH adds in the name of the ME'IL TZEDAKAH (#93) that even if the wife is no longer capable of bearing children and they will never have a second child, Beis Din still does not force him to marry another wife.
(b) There are several opinions with regard to the practical application of this Halachah.
1. The SHULCHAN ARUCH (EH 154:10) cites the RIF and RAMBAM who rule that Beis Din forces the man to divorce his wife after ten years of childlessness. Other Poskim, however, limit -- or entirely eliminate -- this practice:
2. RASHI, the HAGAHOS MAIMONIYOS, and others rule that this Halachah applies only in Eretz Yisrael and not in Chutz la'Aretz (see previous Insight).
3. The Hagahos Maimoniyos (Hilchos Ishus 15:4) adds in the name of the AVI'ASAF that nowadays even in Eretz Yisrael Beis Din may not force a man to divorce his wife after ten years of childlessness. The Gemara in Bava Basra (60b) relates that the Chachamim considered enacting a prohibition against marriage when the nations began to persecute the Jewish people. They reasoned that it is better for the Jews to cause their own end by not having children than to be destroyed by their enemies. The Chachamim, however, decided against such an enactment on the grounds that it would have been too difficult for the people to observe. Nevertheless, the very proposition of such an enactment shows that nowadays Beis Din is not required to force a person to fulfill the Mitzvah of Piryah v'Rivyah.
4. The REMA (EH 154:10) concludes that nowadays it is not the practice of Beis Din to use force (in this matter and in any matters of Ishus). Should, however, the man himself voluntarily divorce his wife l'Chatchilah?
The PISCHEI TESHUVAH cites the SEFER BIGDEI KEHUNAH (#1) who rules that if a man's wife is G-d-fearing and they are happily married, they may remain married even l'Chatchilah and rely on the opinions which maintain that in Chutz la'Aretz one does not need to divorce his wife. He may also remain with his wife based on the logic that he does not know for certain that the source of the problem is his own inability to bear children (and thus divorcing her and marrying another will not help).
RAV MOSHE STERNBUCH shlit'a (TESHUVOS V'HANHAGOS 1:790) points out that this was the practice of many great Torah scholars who, unfortunately, were unable to have children. Rav Sternbuch adds that even when the man and his wife live in Eretz Yisrael, it is impossible to know for certain that it is not one's sins which cause him not to have children, as we are all so sullied with sin. (In his responsum, Rav Sternbuch describes a number of Segulos which he recommends for couples trying to have children.)