2,050. A Woman Who Jokes About Her Status

Hilchos Issurei Biah 4:9

If a woman’s period arrives at a regular time, her husband can assume that she remains permitted until she tells him otherwise or wears the clothes typical of a niddah in her neighborhood. If a woman’s husband travels abroad while she’s ritually clean, he need not ask her about her condition upon his return. Even if she’s asleep, he may approach her for relations so long as it’s not the time when she expects to menstruate and he need not be concerned that she might be a niddah. If she was a niddah when he left, she remains prohibited to him until she tells him that she’s ritually clean.

Hilchos Issurei Biah 4:10

If a woman tells her husband that she’s ritually unclean and later she tells him that she’s ritually clean but she was just joking with him earlier, then her word is not accepted. If she provides a good reason for what she originally said, then her word is accepted. For example, let’s say that a man asked his wife to be intimate but his sister or mother was also with her in the courtyard so she said that she was ritually unclean. Later, she explained that she was actually ritually clean; she just said that she was unclean because she wanted privacy from the sister or the mother. In such cases and similar situations, her words are accepted.