Is marriage a matter of divine decree and destiny (qada' and qadar)? Is a woman's life partner ordained for her since her creation? And will a person, no matter how much they strive, ultimately marry the one destined for them?

Everything Allah has created is by His decree, even inability and capability, and nothing falls outside of Allah Almighty's decree. This includes striving to obtain a righteous wife. Things are predestined with their causes; just as Allah decreed satiation, He also decreed its cause, which is eating. Similarly, He decreed the wife and decreed her cause, which is striving to seek her.