Must a woman obey her husband if he asks her to wear niqab?

assalamu alaykum; so I'm asking this question on behalf of a friend. She is alhamduliLlah a pious muslimah, and wears hijab and abaya. Her husband has just started asking her to wear the niqab. She is a little irritated about it now, because the niqab is not something she is comfortable wearing now, and wearing it everyday would mean she'd have to change her lifestyle quite a bit. Also, her husband had never mentioned this expectation before the marriage or throughout the first year of the marriage. So, should she obey her husband and wear the niqab? and if not, how should she handle this?