Responsa for Kiddushin 161:1

Q. A, of priestly lineage, saw his wife L go to a secluded place with a certain young man. They stayed there only for a short time, for L's mother walked toward them with a lighted candle. On another occasion, while lying in bed late at night, A heard, on the other side of the wall, the heavy breathing of his wife and the young man as they were arduously embracing each other, which to him was clearly indicative of consummated sexual intercourse. The same incident was repeated on another night. On these occasions L was late coming to bed. Next morning, however, when A rebuked L for her lewd conduct, she protested vigorously. Nevertheless A was convinced that his wife commited adultery and was, therefore, forbidden to him. A had always loved and catered to L, but she had never returned that love, and had never submitted to him willingly.
Rabbi Hezekiah b. Jacob, to whom the question was first submitted, ruled that L be forbidden to A.
A. One judge is not at liberty to permit what another has prohibited. Were I present at the time when Rabbi Hezekiah received the query, I would have argued the case with him. A woman is not forbidden to her husband unless either: a) the husband is jealous of a certain man, and warns her against private meetings with this man, and the wife disregards this warning in the presence of witnesses; or b) they actually be found in a position indicative of fornication. But, heavy breathing itself is no indication that illicit sexual intercourse took place. Therefore, I shall wait till Rabbi Hezekiah recuperates from his illness, whereupon I shall discuss this matter with him.
SOURCES: Pr. 98; Am II, 63; Rashba I 832–3; Tesh. Maim. to Ishut, 8; Hag. Mord. Kidd. 549. Cf. Asher, Responsa 32, 11; Weil, Responsa 8; ibid. 88; Israel Bruno, Responsa 5; ibid. 7; Isserlein, Pesakim 222.

R. Isaac left his wife Sarah in the month of Adar of the year 5031 (1271), and travelled to a distant place in search of sustenance for his family. Next year he learned that his wife had played the harlot and had thus become pregnant. He returned home, and in the month of Ab of the year 5032 (1272) he appeared before us and asked us to investigate his wife's conduct during his absence, since she bore a child in the month of Adar of the same year (1272), twelve months after he had left her. Sarah asserted, however, that she was pregnant when her husband left her. Therefore we, the undersigned, wrote to R. Shealtiel and his two sons, who lived in the same village with Sarah, and they testified in writing that Sarah bore a child twelve months after R. Isaac left her. The signatures and seals of the deponents have been attested to by reliable witnesses. Then, a person appeared before us because of the ban (proclaimed against all those who knew anything relating to this case and did not appear as witnesses) and testified that on the evening of Shabuot of the previous year (1271) he went to Sarah's home in order to recite the kiddush in her presence, and found Gentiles, loafers, who caroused with her, caressed and embraced her. We concluded, therefore, that she must have become pregnant at that time. Other persons testified to have seen her on Purim of this year (1272) in the last stages of pregnancy. On previous occasions, however, in the month of Elul, she violently protested that she was not pregnant, and cursed and abused those who had said to her that she was pregnant. Moreover, before the evil report reached the town, Sarah's father appeared before us and asked us to allow him to put his daughter to death by drowning her. When asked for his reasons, he stated that a daughter of his (meaning Sarah) was an incorrigible harlot, who bore a bastard daughter by a Gentile and then killed her child. When asked whether he tried other means of controlling her, he answered that whenever he reproved her she threatened to apostatize altogether and pleaded that she was not the first woman who ever sinned. She had left the house on a number of occasions but was persuaded to return by the entreaties of her mother. The father feared lest she turn to evil and, therefore, asked for permission to kill her. However, we did not permit him to carry out his design. We sent the testimony to Rothenburg to the great luminary, Rabbi Meir. Since the Rabbis of Erfurt who are near us, and those of Würzburg, who are far from us, as well as Rabbi Meir of Rothenburg, all agree to allow R. Isaac to divorce Sarah even against her will, the divorce has been given in our presence. Signed: Moses Azriel b. Eleazar hadarshan, Eleazar b. Yehiel, Ephraim b. Joel.
R. Meir's opinion was as follows:
The testimony of R. Shealtiel and his sons is of no consequence for two reasons. a) They are related to each other; their testimony is that of a single witness, and, therefore, insufficient. b) The foetus could have lingered in the mother's womb for twelve months (cf. Yeb. 80b). Sarah's giving birth to a child twelve months after her husband left her, is, therefore, no proof of her depravity. The testimony of the other witness regarding Sarah's indecent behavior on the evening of Shabuot, being the testimony of a single witness, does not deprive Sarah of her right to her ketubah. If R. Isaac believes the aforementioned witness or if he takes the word of his wife's own father, he must divorce Sarah even against her will. If she renders it impossible for him to divorce her, he may marry another woman without divorcing Sarah as a warning to all indecent and depraved women. But he must pay Sarah her ketubah. However, if Sarah admits her guilt, or acknowledges the truth of the testimony regarding her indecent conduct on the evening of Shabuot, or if she cannot satisfactorily explain why she denied her being pregnant in the month of Elul of the previous year, or answer all other questions regarding her conduct, she loses her right to her ketubah and is entitled only to whatever is left of the valuables she had brought with her upon her marriage.
SOURCES: L. 310; Tesh. Maim. to Nashim 25; Hag. Mord. to Yeb. 121; cf. Sinai vol. V (1941) p. 296; Asher Responsa 32, 11; Weil, Responsa 8; ibid. 88; Isserlein, Pesakim 22.

Q. Ten Jewish adult males were inhabitants of the town of T. One of them wanted to leave [temporarily for the holidays]. His leaving would disrupt congregational prayers. Could the other members compel him to remain?
A. It is an accepted custom throughout the Diaspora for small communities to hire one or two adult males whenever it is necessary to complete a minyan (quorum) for the high holidays. Therefore, if there are exactly ten adult males in the community, the other remaining members can compel the member seeking to leave either to remain in town or to hire somebody else in his stead. But, if there are eleven adult males in the community, no single member can be restrained from leaving; for he does not have to provide for the possibility of another member becoming sick or indisposed. However, if two out of the eleven want to leave, both have to share the expenses of hiring a person to complete the minyan.
Q. When nine Jews have to hire a tenth in order to complete the minyan (quorum), or when they have to hire a cantor for the holidays, do the members share equally in expenses, or do they pay in proportion to their wealth?
A. Since the members do not join a large community for the high-holyday prayers because they do not want to leave their homes, their possessions, and their investments, the forming of the local minyan is dependent upon monetary considerations, and the expenses thereof should be shared by the members in proportion to their wealth.
SOURCES: Pr. 1016; Mord. B. B. 878–9; Hag. Maim. to Tefilah, 11, 1. Cf. Agudah B. B. 15; Maharil, Responsa 107b; Israel Bruno, Responsa 163; Isserlein, Pesakim 243; Judah Minz, Responsa 7.