Safran is Jonathan's grandfather and namesake. We first meet him in Chapter 16 ("The Dial, 1941-1804-1941) on the day of his wedding to Zosha, having sex with Zosha's sister.
That pretty much sets the tone for Safran's entire character. Like Florentino Ariza from Love in the Time of Cholera, he sleeps his way through life. Not Rip Van Winkle-style, but Clooney style.
But it's all fate you see! The universe wants him to be a total man-ho. He was born with teeth, which made it difficult for his mother to nurse him, which meant his right arm shriveled from malnutrition, which meant he was irresistible to the ladies. (Yeah, we don't quite get it, either.)
For some reason, all his paramours (132 if you want to get specific) are turned on by his shriveled baby arm: "His arm […] caused Augustine to fall in love with him and save him, and it saved him once again, years later, when it prevented him from boarding the New Ancestry to Ellis Island" (20.5). Good move: the New Ancestry ended up taking all its passengers straight to a concentration camp instead.
Like Marquez's hero, Safran loves one woman, and only one woman, despite all his dalliances. He falls in love with an unnamed Gypsy girl (presumably he knows her name…we hope…) at the theater. They're together for seven years, at which point he ups and marries Zosha. And the Gypsy girl? She kills herself.
The thing is, Safran doesn't realize that he loves the Gypsy girl until he has sex with his wife while bombs fall near Trachimbrod, signifying World War II's encroachment on Ukraine and the beginning of the end for all the mostly Jewish villages in the area.
If you ask us, this pairing of sex and war is highly symbolic. Love, at least Safran's kind of love, is destructive. Jonathan Safran Foer (the character) doesn't seem very sympathetic toward his grandfather and his promiscuity. He writes "They loved him and he fucked them—ten, jack queen, king, ace—a most straight and royal flush" (24.9). The women see Safran as a person; he merely sees the women as cards in a deck. He has sex with 52 virgins, the number of cards in a deck (and, coincidentally, the number of men who petitioned to be Brod's father over a hundred years prior).
On the day of his wedding, he runs to the house of Lista P, one of his widows (and the woman who becomes Not-Augustine) and whines to her that he's lonely. She tells him the obvious: you're surrounded by family and by women. But he says, "To feel alone is to be alone" (26.136). Should we feel sorry for him? Isn't he making himself lonely?