A missionary needs a missionary wife. A pastor need a woman of peculiar qualifications. So does an evangelist. So do farmers. Also, all classes.
Marriage is generally a mere matter of self-pleasing.
Premature marriage has often proved the ruin of the place and usefulness of the parties. Union in taste and sympathy essential to happiness and usefulness. If the husband's calling or field does not suit his wife, she will not help but hinder. Also, if not suited to his constitution. Or, to his education and qualifications.