IPA: /ˌʌn.rɪˈleɪ.tɪd/
KK: /ʌnˈrɛleɪtɪd/
Not connected or associated with something else; having no relation or link.
The two events are completely unrelated and happened at different times.
Unrelated → It is formed from "un-" (meaning not) and "related" (from Latin "relatus", meaning brought back or connected). The word "unrelated" means not connected or not associated with something.
Think of 'not' ('un-') being added to 'connected' ('related') — that's why unrelated means not connected.