Heterosexuals - does it occur to anyone some couples may want full fidelity whilst others may both prefer free-rein?

This is for heterosexuals only. I've been thinking: at least in theory, it is valid to consentually be exclusive to each other, or to agree to 'yes, you can copulate with others when you'd like that'.

The point being it is far better (and safer) to agree on this than to go 'cheating'.

Thoughts?

Heterosexuals - does it occur to anyone some couples may want full fidelity whilst others may both prefer free-rein?
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