Yichud with one's wife when she is a niddah

Hi,

We have said that a man may not remain in seclusion with a woman to whom he is prohibited.

Nonetheless, a man may be alone with his wife when she is a niddah; we assume that their restraint will be sufficient, because they have been together sexually before and because they know that in a short time they will be permitted to each other again.

(Shulchan Aruch Even haEzer 22:1)

Have a great day,
Mordechai