Is severe distress and quarrels within the home, and the presence of a jinn (demon) or evil eye—as mentioned by the sheikhs—and the impact of these on matters such as marriage and work, a divine decree that can only be removed by Him, or is there a cure for it?

One should not rush and overstate attributing problems to magic (sihr); rather, one must consider the apparent causes and treat them through lawful means. If the existence of magic or possession (mass) is proven, its cure is through maintaining the prescribed ذكر (dhikr) and lawful ruqyah (definition), and relying upon Allah. Everything that occurs in the universe is by Allah's decree, but belief in divine preordainment does not negate taking lawful means. Supplication (du'a') is a means to repel tribulation and attract mercy. Therefore, be diligent in taking means, rely upon Allah, and increase in supplication.