The phrase "Diya hai khara" refers to bitterness or poison. The singer feels cheated. He did everything right: he accepted the pain, he welcomed the dreams. But the beloved turned the relationship sour without any reason ( bewajah ). This creates the central conflict of the song—unjustified abandonment.
Unlike a typical romantic ballad, this song dwells in the "blues." It accepts that while love is beautiful, it comes with a heavy price.