Why does man fear God and not feel love towards Him, and is the relationship with God based on self-interest (worship for the sake of Paradise)?

Love for Allah Almighty branches from knowledge of Him. It is not possible to love Allah without knowing Him, nor is it possible to truly know Him and then not love Him. To come to know Allah, one should begin with the Holy Quran. Whoever reflects upon Allah's names, attributes, and actions will love Him, because love for something arises from its perfection in its essence and actions, and Allah possesses absolute perfection. Similarly, contemplating Allah's creations and blessings increases one's knowledge and love for Him. Ibn al-Qayyim explained that rejoicing in Allah's grace and mercy follows from rejoicing in Him, Glorified be He, and that the believer rejoices in his Lord more than anything else. And whoever places his desire in Allah, Allah will suffice him in every important matter and take charge of all his affairs. Thus, knowledge of Allah and love for Him are ends in themselves, and Allah is worthy of worship by virtue of His essence and perfection.