To expand: in Hebrew and Christian scripture, marriage is used as an analogy for God. For example, the creation story says humanity is created "in the image of God, male and female". God is said to be the husband of Israel; Hosea and others liken Israel to a prostitute or an unfaithful wife. The church is called "the bride of Christ".
Thus, sexual ethics tie directly into core tenets of Judeo-Christian doctrine relating to who God is and how God relates to humanity. Concepts like faithfulness, self-sacrifice, love, authenticity, exclusivity, the joining of two different beings into one coherent whole, and commitment are reflected in both Theology and sexual ethics. This is communicated in Jewish and Christian scripture, and in the writings of Jewish and Christian scholars throughout history.
There are components of Jewish and Christian sexual ethics that can be thought of in terms of harm (cheating on your spouse can harm them emotionally, or physically through STDs), but for the most part it's more appropriate to think in terms of a reflection of God's nature and interaction with humans. For someone whose education in ethics is limited to harm, it can be difficult to see how ethical systems could be built around other concepts, but once you grasp the basic philosophical core, it's pretty straightforward to see how sexual ethics fit.
Thus, sexual ethics tie directly into core tenets of Judeo-Christian doctrine relating to who God is and how God relates to humanity. Concepts like faithfulness, self-sacrifice, love, authenticity, exclusivity, the joining of two different beings into one coherent whole, and commitment are reflected in both Theology and sexual ethics. This is communicated in Jewish and Christian scripture, and in the writings of Jewish and Christian scholars throughout history.
There are components of Jewish and Christian sexual ethics that can be thought of in terms of harm (cheating on your spouse can harm them emotionally, or physically through STDs), but for the most part it's more appropriate to think in terms of a reflection of God's nature and interaction with humans. For someone whose education in ethics is limited to harm, it can be difficult to see how ethical systems could be built around other concepts, but once you grasp the basic philosophical core, it's pretty straightforward to see how sexual ethics fit.