亀裂

1. Origins, structure, and basic meaning

• Structure: 亀裂 (きれつ) is a noun for a crack in a hard surface or a serious figurative fracture in a relationship.
• Basic usage: 壁に亀裂が入る describes a physical crack after an earthquake, while 信頼関係に亀裂を生む has a small misunderstanding damage trust.

2. Common pitfalls and similar expressions

• Structural crack and relational breach
  • 亀裂が入る is structural damage, whereas 亀裂を生む is a metaphor for discord. No literal line-shaped gap forms in the relationship.