Are connection and the matter of marriage preordained by Allah Almighty before we are born, and is contracting cancer a result of not observing Allah's regulations and being excessive in choosing a partner, which indicates Allah Almighty's displeasure?

One of the pillars of faith in divine decree (qadar) is the belief that Allah inscribed the destinies of all creatures fifty thousand years before the creation of the heavens and the earth. This instills tranquility and trust in Allah, and motivates one to strive while relying on Him. Faith in divine decree prevents sorrow over what has passed, and encourages correcting mistakes and diligent effort in pursuing means. Illness is not a sign of Allah's displeasure; rather, what afflicts a person is a trial from Him. "Indeed, the greatest reward comes with the greatest trial. And indeed, when Allah loves a people, He afflicts them. Whoever is pleased, for him is pleasure; and whoever is displeased, for him is displeasure." Your patience and contentment indicate Allah's pleasure. We advise you to supplicate and take the necessary means, and know that the reward for patience is immense.