suitable age; marriageable age
Primarily used for the age considered appropriate for marriage, but can also refer to the right age for other life events.
彼女はもう適齢期を過ぎている。
She is already past the marriageable age.
適齢期になったら結婚したい。
I want to get married when I reach the right age.
She has already reached marriageable age.
The number of unmarried people who have passed marriageable age is increasing.
The right age for marriage differs from person to person.