1. Extravagant enthusiasm.
2. Excessive sentimentality.
From Schwärmerei (enthusiasm), from schwärmen (to swarm, to be wild or mad about). Earliest documented use: 1845.
“True fulfillment flowed solely from whatever they had in common, for that was always a condition of schwarmerei.”
Jonathan Thomas; Midnight Call and Other Stories; Hippocampus Press; 2008