And now is clear how Arie van Greuningen and Johanna Margaretha Stuffers met...!!!
He met her through the family of his first wife.
Arie's first wife, Engelina Hendrika Kornelia Kroon, was the daughter of Kornelis Kroon and Lijntje Kroon.
Maria Kroon, married to Abraham Gerardus Stuffers (brother of Johanna M), was also the daughter of Kornelis Kroon and Lijntje Kroon.
So the second wife of Arie is the sister of his sister in law's husband.
I guess they must have met during a family gathering, birthday celebration or something like that.