Which part confuses you specifically? I can’t understand your complaint here. “No kids need to focus everything on money because simply enjoying life won’t change the world (nothing ever will)”??
My wife and I talked about it a lot before deciding we were both cool with the other having safe and responsible adventures. In over a decade it has never caused us any grief. Communication is essential and if your relationship isn’t “stable” IMO it suggests a real communication problem - adding unrelated complications to the dynamic will never solve those.