"You're not alone", they cheer you up. Yes, they always do. They always make you feel special when your world is crumbling down to pieces. Then, when you're bucked up, firm on your feet, they leave. As quick as lightning, as gentle as wind, gone.
"You're not alone." they'll say. But who are they? You tell yourself, they'll say this, they'll do that. Who then, are they? 'They', unfortunately do not exist. 'They' is your conscience, your inner voice, yourself. There is no 'they', because whenever you're hurt and lonely, you'll tell yourself, "They'll tell me it's going to be okay, they'll tell me I'm not alone", they won't. So, that leaves you to tend to your sorrows on your own.
You are alone. We are alone.
They is singular.