Sforno on Deuteronomy 22:13/ספורנו על דברים כ״ב:י״ג

1כי יקח איש אשה, after the Torah has dealt with matters concerning the settling of the people in the Land of Israel, it turns to instructions designed to ensure that the Shechinah, benevolent Divine presence, will maintain its beneficial presence there. One of the most important elements in ensuring this is the avoidance of forbidden mating and the offspring of such couplings. The Torah therefore addresses both forbidden incestuous relations amongst Jewish partners, and intermarriage or living together of Jews and Non-Jews without the benefit of “marriage,” something which is anyway legally impossible. All of this belongs to the headingוהיה מחניך קדוש ולא יראה בך ערות דבר ושב מאחריך, “your encampment shall be holy. Let nothing unseemly be found among you so that He would turn away from you.” (23,15)