How will the believer be happy in Paradise if his non-Muslim family members are in Hell?

Islam is the religion accepted by Allah after the advent of Prophet Muhammad, peace and blessings be upon him. Allah perfected it and was pleased with it for His servants. No one is held accountable for another's sin, and Allah does not punish anyone until proof has been established against them through the sending of a messenger. Whoever has been reached by Islam and does not embrace it has wronged himself and deserves eternity in Hellfire if he dies upon disbelief. Allah does not unite the believer and the disbeliever in Paradise, and even if children enter Paradise while their parents were disbelievers, they will not grieve because Paradise is a abode of joy, devoid of sorrow and imperfection.