thoughtless

Unless said partner is ready to be whacked over their head with the box for their thoughtlessness, they have made a grave mistake.

Thoughtlessness regarding his neighbours is not a poor man's vice.

While terrified leaders passed from arrogance or thoughtlessness to dejection and confusion, the blow was being struck.

Then having thus spoken, they lay down out of the pathway among the dead; but he, in thoughtlessness, ran hastily past.