Is a wife entitled to demand that her husband spend more time with her, apart from the night he spends with her? And is a wife held accountable if she sleeps by herself?

The husband must be just between his two wives concerning their night stays, and this includes both night and day. He is not allowed to prefer one over the other unless the other consents. It is permissible for the husband to visit the other wife during the day for a need, such as paying maintenance or visiting her, but he is not allowed to do so without a need. If he does so and prolongs his stay, he must compensate the other wife for that duration. A wife abandoning her husband's bed without a valid excuse is an act of disobedience, unless the husband is oppressive in his abandonment of his wife.