Sex is a privilege because we have a choice to participate in hsveibg sex or not as well as pick and choose our partners..
However,
When it comes to being in a relationship, especially a monogamous relationship, then said privilege becomes a priority, if said individuals who chooses to be in such relationship expects fidelity..
No sex, no exclusivity! No sex, no relationship! Sex should not be used as a bargaining chip nor should relationships be transactional, but unfortunately, it is for some to many relationships which is why many relationships fail...
The choice(s) lies with the individual..