The phrase "unrelated event" refers to something that is not connected or has no association with another event or situation.
Sentences with «unrelated event»
These pivotal moments can happen from seemingly unrelated events. (moderncommitment.com)
Instead they created a series of unrelated events sharing a central design. (kotaku.com)
This mantra has been with me for a while but it's taken a bit of a back seat of late thanks to two completely unrelated events. (travelingformiles.com)