A seemingly strong alliance can quickly fall apart when divine intervention alters the course of events. After only a short period, the partnership between Abimelech and the leaders of Shechem begins to sour, leading to the complete collapse of their pact. God steps into the situation, actively causing a deep rift that sets the stage for treason.
The primary approach among commentators is that this divine intervention manifests as a state of intense hatred and severe strife. Because of this sudden, overwhelming enmity sent by God, the relationship between the two parties rapidly deteriorates. Driven by this hostility, the leaders of Shechem completely turn against Abimelech, resulting in an act of outright betrayal.