How do citizens find their matching spouses in The Giver?

Jonas's uniform, highly structured society is founded on the principles of Sameness and tightly controlled by the Committee of Elders. The Committee of Elders is responsible for making every significant decision in the community, which includes controlling the birthrate, matching spouses, organizing households, and deciding specific occupations for each citizen in the community. In Jonas's society, independence and human agency are virtually nonexistent. Citizens do not get to choose their spouses and must apply for a spouse. After applying for a spouse, the Committee of Elders carefully examines the citizen's personality traits and compatibility factors in order to choose the perfect, most compatible partner for them. The citizens have absolutely no say in who they marry and the Matching of Spouses is controlled by the Committee of Elders. Once a couple is matched, they are monitored for three years before they are allowed to apply for a child, which is also out of their control and chosen by the Committee of Elders.

In The Giver, everything is controlled, from what jobs the citizens have to how many children they can raise. One example of this is the ceremony called the Matching of Spouses. The Committee of Elders, who run the society, oversee these kinds of ceremonies. Just like they determine what job each twelve-year-old is best suited to, they also assign spouses. The Committee of Elders considers each person's personality, as well as "disposition, energy level, intelligence, and interests." A person can apply for a spouse, and it may take a long time before the Committee of Elders decides upon a suitable match. They want the husband and wife to complement each other.
Once a pair has been married and observed for three years, they may apply for children. They can be granted one male child and one female child, who are birthed by Birth Mothers.
In this society, citizens don't have choice, because the Committee fears that people will choose wrong. They cannot choose who they marry. Their spouse is assigned to them.