Is a wife excused for delaying her Maghrib prayer past its time due to a problem with her husband, and is she sinful for it?

A believer must perform prayer at its appointed time, for it is an obligation specified by a fixed time, as Allah Almighty said: "Indeed, prayer has been decreed upon the believers a decree of specified times." [Quran 4:103] Marital disputes do not justify negligence in prayer; rather, they emphasize the importance of maintaining it. Allah Almighty said: "Maintain with care the [obligatory] prayers and [in particular] the middle prayer and stand with obedience to Allah." [Quran 2:238]