He lectured his son and wrote: "Your mother and I could not but to like the person of the Lady Margareta and would with much pleasure like her as a daughter-in-law. However, we would not like to see all hope to have grandchildren by You vanish by Your marriage to her. You are our oldest son and after God our only hope and support. You are young still, hardly thirty-five, and I cannot understand why You would burden Yourself with an old and barren woman and thereby do what You may regret." But Johan Oxenstierna was genuinely in love, wished to marry Margareta exclusively for emotional reasons and refused to consider political, economic or fertility reasons, and in July 1648, Johan Oxenstierna and Margareta Brahe eloped to Wismar in Germany, where they were wed. As the marriage was neither political, economic or intended to produce children, it was an obvious love match, which was controversial in an epoch where marriage was normally not conducted for love: it took place but four months after the death of the groom's first wife, and it also caused a scandal because of the age difference, when the bride rather than the groom was one decade senior. The couple remained in Germany, where Johan Oxenstierna was a Swedish delegate during the Congress of Osnabrück, and Margareta Brahe reportedly played an important part during the Peace of Westphalia through her calming influence upon her hot-tempered husband, which benefited the sensitive negotiations. Johan Oxenstierna himself alluded to this in letters to his father: "I may admit, that if my wife had not been here, I would surely already have been lost." The marriage was evidently happy, but childless. On 5 December 1657, Margareta Brahe became a childless widow a second time. The death of her second husband reportedly caused her such sorrow that she was confined to her bed for a long time. After the death of her second spouse, Margareta Brahe was one of the richest people in Sweden. Her husband had inherited the 'Sture Inheritance' from Ebba Leijonhufvud (the mother of his first wife, heiress Anna Sture), and left all of it to Margareta Brahe in his will, and though she gave up some of it in a settlement with the relatives of Anna Sture in 1661, she had become very rich and thus an attractive marriage partner.