Is a husband obligated to command his wife to wear the hijab as a fard (religious duty), even if he fears a negative reaction, or is there another way to approach this, especially since she abstains from or procrastinates in wearing it, claiming she is not convinced or ready for it?

A woman's abstaining from wearing the hijab or procrastinating in doing so is a grave dereliction of a great duty, one of the major sins, because it is an obligation upon the Muslim woman. The husband must remind his wife of the obligation of the hijab and the urgency of wearing it, and clarify the consequences of neglecting it. If she refuses and insists [on not wearing it], then he must separate from her, for remaining with her while she persists in this is a form of cuckoldry (dayatha).