The fifth way in which we afflict ourselves [on Tish’a B’Av] is by refraining from marital relations. In order to avoid stumbling in this matter, a couple must act on the night of Tish’a B’Av as they do when the wife is a niddah (a menstrual woman). That is, they may not touch each other, sleep in the same bed, or pass things to each other from hand to hand, [etc.]. During the day, however, they need not observe all the precautionary measures that are in place when a woman is a niddah, but affectionate touching and sleeping in the same bed are still forbidden.[13]
[13]Sh.A. 554:18. Two conjoined beds are considered one. The Acharonim write that one should act stringently on Tish’a B’Av with regard to all the precautionary measures [that couples keep] during the niddah period, just as one does on Yom Kippur (Sh.A. 615:1). According to the majority of poskim, one should act stringently both on the day and night of Yom Kippur. The Taz holds that one need not be strict during the day of Yom Kippur. When it comes to Tish’a B’Av, however, many poskim write that one need not be careful during the day, because everyone is mourning and the women do not adorn themselves; therefore, there is no reason to fear that [contact between husband and wife] will lead to sexual intercourse (M.B. 554:37, K.H.C. 85). There are those who rule strictly even during the day when it comes to touching (Kitzur Sh.A. 124:12, Hilchot Chagim 26:49). Either way, it seems [to me] that everyone agrees that affectionate touching is forbidden even during the day, as is sleeping in the same bed.
