Is creating hickeys a sex related act?

Answer 1

To answer a question with a question.

Who creates a hickey on someone they don't fancy sexually?

Yes its a sexual act.

If its done in a visible place (and mostly it is) its a way of branding someone as a sexual partner.

Answer 2

Creating hickeys, also known as "love bites," is often considered a sexual activity. Though it can be a consensual act between partners, it primarily involves sucking or biting on the skin to cause bruising. The purpose is usually to leave a visible mark on the body, often on the neck or other sensitive areas, which can be seen as a form of sexual or intimate expression.