Bhagavad Gita, Chapter 18, Verse 38

That which arises from the contact of object with sense, at first like nectar, but at the end like poison, that happiness is declared to be Râjasika.

The exact opposite pattern is named here, real sweetness up front, real bitterness once it's over.

Krishna mirrors the previous verse's structure precisely to make the contrast unmistakable. Real short-term pleasure and real long-term cost are shown as directly linked.