He got married last week , so i think sending them explanation would be a great idea bcz he already waited 24 months for ainp and another 18 for federal.It depends on how long her background check is going to take. If he got married less than a month ago, he could add a letter to CIC to explain that he would like to sponsor her later. CIC MAY then issue COPR for him alone.
I hope they will send him COPR and he can sponsor her later.