Is fear of unseen matters, such as losing a loved one or failure, considered among the forbidden types of fear or shirk of love? And are there specific supplications to be recited for such fears?

This fear is not among the forbidden fears that lead to committing haram acts, nor is it from the shirk of love. Rather, it is a permissible love of compassion, familiarity, and intimacy. The cure for this fear lies in relying on Allah, trusting Him, having full conviction that all matters are in His hands.

We advise consistently reciting the established dhikr and invocations for protection of oneself and family, such as the invocation for Hasan and Husayn, the supplication for well-being in this world and the hereafter, and saying "Hasbiyallahu la ilaha illa Huwa 'alayhi tawakkaltu wa Huwa Rabbu al-'Arshi al-'Adheem" (Allah is sufficient for me; there is no god but Him. On Him I have relied, and He is the Lord of the Mighty Throne) seven times in the morning and evening.