Is it normal for a 21-year-old girl to desire marriage, and for that to affect her psyche?

A person's life is their capital, which should be invested in the remembrance of Allah, fulfilling obligations, diligently performing recommended acts, associating with the righteous, and reflecting on this world and the hereafter. One should not be preoccupied with what Allah has already decreed (Divine Decree). The Prophet, peace and blessings be upon him, guided young people who were unable to marry to fast. Therefore, the questioner is advised to continue fasting, to be patient with Allah's decree, and to turn to Him for the facilitation of marriage.