Is there a solution to the problem of not feeling paternal emotions and longing towards children and wife, despite having two children and a stable marriage?

Compassion and mercy towards children are innate. Allah sent down one mercy to foster affection among creation, and people vary in the extent of this mercy. Whoever shows no mercy will not be shown mercy, and hardness of heart removes mercy. A Muslim should be affectionate towards his children and wife, for children are a great blessing and have material and moral rights. If a lack of affection towards them is something a servant does not control, then Allah unites hearts, and there is no sin upon him for that.