While a poured cup of wine normally brings joy to the heart, it is used as a dark metaphor for future troubles and impending disaster [רד״ק]. This specific cup is one of wrath. Consuming it leads to a devastating drunkenness that strips away reason, leaving the drinker overwhelmed by confusion, sadness, and deep grief [מצודת דוד, מלבי״ם]. The intoxicating effect of this bitter drink is understood to be the very grief itself [רד״ק].
As the tragedy takes hold, it brings profound bewilderment to the heart [רש״י, מצודות], which is closely tied to the physical destruction of the land [ביאור שטיינזלץ]. This devastation will leave the area in a state of absolute ruin, representing a severe and escalating form of destruction [מלבי״ם]. Ultimately, the city is destined to suffer the exact same fate of confusion and desolation that previously befell the royal city of Samaria [מצודת דוד, מלבי״ם].
This impending disaster unfolds in three distinct, escalating stages. First, the city will be overcome by an intoxicating, paralyzing grief. Second, the disaster will deepen as the land is transformed into an empty wasteland. Finally, the tragedy will reach its peak as the city is forced to endure the ultimate ruin, mirroring the exact downfall experienced by Samaria [מלבי״ם].