Matters that are prohibited during her time of menstruation, including 17 paragraphs: A person is obligated to separate from his wife during the days of her impurity until she counts and immerses (even if she waits a long time to immerse). She is always in her Niddah status until she immerses (Beis Yosef in the name of halakhic authorities). He should not joke or engage in levity with her (even with words) (Tur and Beis Yosef in the name of the Rashba from Avot d'Rabbi Nasan) lest he become accustomed to sin. However, he is permitted to be alone with her since once he has had intercourse with her one time, his urger will no longer overcome him (his own language).
He may not touch her, even with his little finger, nor may he pass anything from his hand to her hand, nor may he accept from her hand, lest he touch her flesh (similarly, by throwing from his hand to hers or vice versa, is also prohibited).
He may not eat with her at the table unless there is some difference, that there is something separating between his plate and her plate, bread or a pitcher, or that each one eats on their own tablecloth. Rama: There are those who say that the requirement of separation between his plate and her plate is specifically when they don't eat from the same plate when she is pure. However if they normally eat from a single plate when she is pure, it suffices if she eats from her own plate, and they don't need another reminder (Hagahot Ashiri in the name of R"i and Hagahot Alfasi) and this is the practice. There are those who say that it is prohibited for him to eat what remains on her plate (found in a commentary on the laws of Niddah) just as it is prohibited for him to drink what remains in her cup, as will be be explained.
He may not drink from what remains in a cup from which she drank. Rama: Unless someone else drank in between them (Tur in the name of the Smag) or it was poured from this cup into another cup, even if it was returned to the first cup (Hagahot Maimoniot in the name of the R'em and the Rokeach 318 and Mordechai and Aguda on the first chapter of Shabbos). If she drank and he didn't know, and he wanted to drink from her cup, she doesn't need to tell him not to drink (ibid), and she is allowed to drink from a cup from which he drank (ibid). If she drank from a cup and left, there are those who say he is permitted to drink from what remains since after she has already gone, there is no obligation (in the commentary mentioned above).
He should not sit in a bed that is specifically meant for her even in her absence. Rama: It is prohibited to sit on a long bench that wobbles and is not attached to the wall when his wife in Niddah is sitting on it (Mordechai first chapter of Shabbos, Tzaphenas Paneach in the name of Rashi) but there are those who permit when a another person sits in between them (Agudah on Chapter Hatinoket and Torat Habayit 251). Similarly, he should not go with his wife in a single cart or on a single boat if they are going just for a pleasure trip, for instance to go to gardens and orchards or the like. However, if he is going from one city to another out of necessity, it is permitted, even if he and his wife are alone, as long as they sit in such a way that they do not touch each other (all this is in Torat Habayit 251).
He may not sleep in bed with her, even if each one is in their own garment, and they do not touch each other. Rama: Even if each one has their own sheet (Beis Yosef contrary to Rabbeinu Yorucham), and even if they sleep in two beds but the beds touch each other it is prohibited (Mordechai on Chapter 1 of Shabbos in the name of the Ram).
He may not gaze even at her ankle, nor at any of her covered places. (However, he is permitted to gaze at her revealed places, even though he takes pleasure in the sight) (Beis Yosef in the name of the Rambam).
It is fitting that she should have special garments for her days of Niddah so that they both remember constantly that she is in Niddah.
With difficutly, they permitted her to adorn herself during her days of Niddah, only so that she should not be repulsive to her husband.
All labors that a woman does for her husband, a Niddah may do for him, except mixing his cup, for it is prohibited to mid the cup (in front of him) (Beis Yosef and similarly is implied in the Mordechai on the first chapter of Shevuos and several places in the words of the halakhic authorities), or setting on the table before him unless she makes a reminder, for instance that she sets it on the table on the left side or that she sets in on a cushion or pillow, even on his right hand side.
She is prohibited to make his bed in front of him, specifically spreading sheets and blankets, which is in the way of affection, but setting out the pillows, which is labor and is not the way of affection, is permitted. In his absence it is all permitted, even if he knows that she is making the bed.
She is prohibited to pour water for him to wash his face, hands and feet, even if she does not touch him, and even if the water is cold.
Just as she is prohibited to mix for him, so, too, he is prohibited from mixing for her. Not only that, but even to send her a cup of wine. It doesn't matter whether it is the cup of blessing or another cup, if it is designated for her. However, if they are drinking out of that cup, and she drinks after him, we need not be concerned.
All these distancing measures must be practiced both during her days of menstruation and during her "whitening" days, which are all the days of her counting, nor is there a distinction in any of these, between one who experienced a flow and one who found a stain. Rama: There are those who say that we need not be stringent during her whitening days in the matter of the prohibition on eating with her from a plate (note in the Mordechai in the name of the Raavya), and thus the practice is to be lenient in this, but one should be stringent.
If he is sick and has no one to attend him besides her, she is allowed to attend him, but she should be as diligent as she can be to avoid washing his face, hands or feet, or making the bed in front of him.
A woman who is sick and menstruating, it is prohibited for her husband to touch her in order to attend to her, for instance to help her stand up, or lie down, or to support her (there are those who say that if she has no one else to attend her, he is permitted to do everything and this is the practice if she really needs it).
If her husband is a doctor, he is prohibited to touch her in order to take her pulse. Rama: According to what I have written, that our custom is to permit him to attend her if she needs him, all the more so, it is permitted for him to take her pulse if there is not another doctor, and she need him, and there is danger in her illness (thus specified the Beis Yosef from the language of the Ramban 127), and see in Orach Chayim Ch. 88 if a menstruant is permitted to enter a synagogue to pray.