Decide what you are ending
You may want to stop the sexual relationship but keep the friendship, or you may need distance from both. Know which boundary you are communicating.
Be direct and brief
You do not need a courtroom argument. Say that the arrangement no longer works for you and what you want to happen next.
Do not offer false hope
If you know you do not want to resume later, avoid leaving the other person waiting on a vague “maybe someday” solely to soften the moment.
Give the friendship room
Returning immediately to the old friendship may not work, particularly if feelings are involved. Space can be a respectful choice.
Sexual-health follow-up
If there is relevant health information that should be shared after the relationship ends, communicate it. Ending the relationship does not erase that responsibility.
Separate the feeling from the decision
A change in emotion does not dictate one mandatory next step. Attraction can deepen without requiring a committed relationship; jealousy can appear without making exclusivity the right solution; reduced interest can happen without anyone doing something wrong. First identify what changed, then decide what you actually need. That distinction helps you communicate a request instead of presenting an emotion as a demand.
Make room for a different answer
Transitions become easier to navigate when both people are allowed to want different outcomes. One person can want commitment while the other prefers to stay casual. One can want friendship after ending the sexual relationship while the other needs distance. The next step should be based on what is mutually workable, not on forcing symmetry where it does not exist.
Labels help describe a relationship, but expectations are specific to the people in it. When something important changes, a direct conversation is usually more useful than trying to decode a rule from the internet.