What is the next line in the phrase "looking for him in a thousand places, suddenly looking back"?

The next line of the poem is "The man is in the place where the lights go out".

This poem is from "The Case of the Green Jade" (青玉案-元夕), written by Xin Qiji, a famous lyricist of the Southern Song Dynasty.

The Case of the Green Jade - The Night of the New Year

The east wind releases thousands of flowers at night. The stars are like rain. The BMWs and carvings filled the road with fragrance. The first thing you need to do is to get your hands dirty. The smile is full of dark fragrance to go.

Searching for him in a thousand places. I'm not sure if I'm going to be able to do that, but I'm going to be able to do it.

Xin Qiji (May 28, 1140-October 3, 1207), formerly known as Tanfu (坦夫), later changed his name to You'an (幼安), and called Jiaxuan (稼轩), was a native of Lixing County, Lixing Prefecture, Jinan Province, East Shandong Province, and the village of Sifengzha (四凤闸, Si Feng Zha, Yuanwang Town, Lixingcheng District, Jinan City, present-day Jinan.

Southern Song Dynasty, a bold and liberal lyricist and general, was known as the "Dragon of Lyrics". He was known as "Su Xin" together with Su Shi, and "Jinan Er'an" together with Li Qingzhao.

Kaixi three years (1207), Xin Qiji died of illness, aged 68. Afterwards, he was awarded the title of Master, posthumous name "Zhongmin".