The Torah says God took "one of his ribs" to make the woman. Targum Pseudo-Jonathan on (Genesis 2:21) gets oddly specific. "He took one of his ribs, it was the thirteenth rib of the right side, and closed it up with flesh."
Why the thirteenth? Jewish mystical tradition treats the number 13 as sacred — the numerical value of echad, "one," and of ahavah, "love." The Targumist may be signaling that Eve was taken from the seat of unity and love in Adam's body. The human marriage will carry that signature forever.
And the right side matters. In Jewish symbolism, the right hand is the side of kindness (chesed). The woman is not formed from the left — the side associated with gevurah, severity — but from the side of compassion. The Targumist is quietly saying that the partnership of husband and wife is rooted in kindness from its first breath.