Is the husband sinful for divorcing his wife who refuses to wear the hijab and cheats on him, given that they have a daughter, and is it better for him to stay with her?

The husband must oblige his wife to be modest and chaste and prevent her from committing reprehensible acts if she is suspiciously conversing with a non-mahram man, not wearing the legal hijab, and sending her picture to him, by virtue of his guardianship.

If she repents and becomes upright, it is better to keep her; otherwise, he should not keep her, and divorce may be obligatory in such cases.