Many women feel they owe extensive explanations for decisions: declining an invitation, ending a relationship, changing jobs, taking time off. The over-explanation is usually anxiety, not politeness. Brief honest statements close conversations; long justifications invite debate.
What over-explaining costs
Invites negotiation. Provides ammunition for objections. Suggests the decision is up for debate. Drains your energy in justifying what you've already decided.
What brief statements look like
'No thank you, I can't make it.' (Period. Don't add reasons.) 'I've decided to leave the company.' (Don't justify; you've decided.) 'I'd rather not discuss that.' (Boundary stated; no justification needed.) Most adults accept brief statements without pressing.
Notice the instinct to justify. Most justifications add nothing except invitation to debate. Brief and clear is usually kinder for everyone.