Acceptance Does Not Require Fatalism
After an event occurs, one statement becomes undeniable. That is what happened.
The fact is retrospective. It does not tell us that the event was fated. It does not tell us that no other outcome was possible. It does not tell us that action made no difference. Those are additional philosophical claims.
Acceptance becomes confused with fatalism when the two are collapsed. To accept a missed deadline is to stop arguing with the fact that the deadline was missed. It does not mean the miss was destined. It does not mean planning is useless. It may produce exactly the opposite response: a more accurate plan.
Agency operates before and during events through choices, constraints, interactions, and consequences. Acceptance operates afterward by acknowledging what has become fact.
The future remains open to action even though the past no longer is. What happened happened. That sentence requires no theory of fate.