Albert Magh's poem is a single sentence, but it holds a whole arc of regret. The speaker looks back at a stretch of time spent in happiness, and the tone is not celebratory. "Squandered" is the key word: the bliss was real, but the speaker feels they wasted their time on it and lost their bearings. Being "lost in the light" suggests something dazzling that blinded as much as it warmed.
Now the speaker is still lost, only in a different place. Pain is "departing," which could mean it is slowly leaving, yet the speaker is stuck "in the midst" of it, caught halfway between suffering and relief. The title, "Agony In Bliss," puts the two feelings side by side, hinting they were never fully separate.
The mood is quiet, dazed, and a little bitter. There is no anger, just the tired confusion of someone who went from one kind of lostness straight into another.