Praise be to Allah, and may peace and blessings be upon the Messenger of Allah. To proceed:
Belief in divine decree is one of the pillars of faith. It includes believing that Allah تعالى knows everything, has written the decrees of His creation, wills whatever comes to pass, and created all creatures and their actions. Therefore, He has decreed what will happen in a person's life, including marriage, children, provision, and other matters.
However, belief in divine decree does not mean abandoning the means or that a person is compelled in his actions. A servant has will and choice, and he must strive for what benefits him. The Prophet ﷺ said: “Act, for everyone will be facilitated toward that for which he was created.” Thus, whoever wants to marry should pursue marriage, whoever wants provision should seek its means, and whoever wants goodness should follow its path.
Regarding marriage, a Muslim should look for a woman who possesses religious commitment and good character, pray istikhara to Allah, and consult experienced people, then proceed with what appears most appropriate to him. If the marriage becomes possible, let him praise Allah. If it does not become possible, let him think well of his Lord and know that whatever Allah has decreed for him is good. The Prophet ﷺ said: “How wonderful is the affair of the believer, for his entire affair is good...” Narrated by Muslim.
What has been written in the Preserved Tablet (Al-Lawh Al-Mahfuz) does not change. Whatever Allah تعالى knew and wrote eternally will certainly come to pass. As for what is recorded in the records of the angels, there may be erasure and confirmation according to what Allah commands. He says:
﴿Allah erases what He wills and confirms, and with Him is the Mother of the Book﴾ [Ar-Ra‘d: 39].
Allah has made acts of obedience and sins causes that produce consequences. Maintaining ties of kinship is a cause of increased provision and prolonged أثر, supplication is among the causes of warding off affliction, and sin may be a cause of being deprived of some provision. All of this is within Allah's decree and His prior knowledge. It does not mean that a servant escapes Allah's decree or changes His knowledge.
It is better not to attach your heart to a particular woman, nor to follow a path that leads to correspondence, conversations, or unlawful seclusion. Rather, ask Allah to grant you a righteous wife and to decree goodness for you wherever it may be.
If you are serious about marrying her, consider the matter in the manner prescribed by Islam, pray istikhara to Allah تعالى, and approach her through her family. If the matter becomes easy, then that is good. If it does not, then turn your heart away from her and know that there are many women, and what is sought is a woman of religious commitment and good character.
And Allah تعالى knows best.