Laws of Immersion in a Mikveh

Shalom and blessings. A woman who does not intend to have any sexual relations with her husband is forbidden to live with him in the same house as long as she has not immersed in a mikveh for purity, due to the prohibition of yichud with a niddah woman. The permission for yichud with any niddah woman is only because she is expected to purify herself and ultimately become permitted. However, if the issue is temporary, such as a medical problem, the poskim write that it is advisable for the woman to purify herself so that they can be permitted in all other forms of closeness; but if the husband fears that in the case of closeness without relations he might emit waste seed, the woman should not immerse and should wait until they can have relations. Nevertheless, a woman who has no medical or other temporary impediment to having relations indeed has a special mitzvah to have relations on the night of immersion. Blessings, Binyamin Shmueli.