When one is emotionally experienced enough and financially stable to handle the challenges and needs of a marriage.
Marriage for me is not a thing to be rushed, since it is a new place we have willingly step in to live for the rest of our lives.
I'll advice that they stay engaged when young and before they get old enough for marriage, they would have known a lot about each other and how to work out their differences to make a great home for their kids. That's my opinion.
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