Rules for accepted and expected behavior. Norms prescribe “proper” behavior. (In a different sense of the word, norms also describe what most others do-what is normal.)
From a heteronormative point of view, the first thing that comes to mind when the word sex is mentioned isn't foreplay or oral sex, rather, it's straight up penis penetrating a vagina. Limiting is an understatement.
It's not all chemical: love can be thought of as an epigenetic phenomenon. From social experiences, emotional attachments, and reciprocal relationships- there is a connection and lots of variation when it comes to environment and biology.
