Reference: Fataawa Mu’aasirah – Page 83
al-Mowsoo’ah – 10237
Question: Is it permissible for a husband to go to his second wife if he has made hajar (temporary boycot) of the first one based upon an Islaamically valid reason, or should he stay with the first one in the house?
Response: For the sake of [equally] dividing (i.e. being just in allocating for each wife a day and a night) it is obligatory that he remains with her (the first one) [during her allocated time], and Allaah [alone] has the Complete knowledge [of all affairs].