Praise be to Allah, and peace and blessings be upon the Messenger of Allah.
Yes. Everything that will exist until the Day of Resurrection is written in the Preserved Tablet, including provision, lifespan, deeds, and marriage. Allah has written the decrees of creation before they occur. This includes what the angel writes for the fetus concerning its provision, lifespan, deeds, and whether it will be among the miserable or the blessed.
Provision is written and decreed, but it is decreed together with its means. Therefore, a person may not abandon striving on the pretext that his provision has already been written. Rather, he must take the lawful means. Among the means of provision are working and seeking lawful earnings, maintaining ties of kinship, and having consciousness of Allah, the Exalted. Allah says:
﴿And whoever is mindful of Allah, He will make a way out for him and provide for him from where he does not expect.﴾ [At-Talaq: 2–3]
Likewise, marriage is written and decreed. Allah, the Exalted, has decreed for every person what marriage they will have, and nothing falls outside His knowledge and decree.
Therefore, the believer combines belief that provision and marriage are decreed and written, with taking the lawful means. He should not use belief in divine decree as an excuse to abandon work and striving for what benefits him in his religion and worldly life.
And Allah, the Exalted, knows best.