The song you may be looking for is "A Person", sung by Lu Yan.
Some of the lyrics are as follows:
Go to work alone
Breakfast alone
Go alone and get used to enjoying loneliness
The other half of the city
Are you also regretful
Also entangled with the past
Working alone
Dinner alone
A person has become accustomed to being alone
I still leave warmth waiting for you in the other half of the world
Say good night to me