Talk to Sexologist on Asexual Husband

Salam, my sister got married in January, she and her husband tried doing sex only twice, in four months of their marriage, husband have lots of reasons to avoid it, like he is too sleepy, too tired, comes late to the room, etc upon confronting him about it he said he is asexual and has no interest in sex but he said he can produce babies, but he don’t want to initiate it so my sister should always initiate. Please can you guide me about Asexual man/ husbands because my sister has a desire of sex and hể doesn’t , are Asexual husbands able to produce babies? Is there any medical condition associated with Asexual man, are they straight or gay? Please answer all the questions ASAP I am worried and her marriage is at stake