I think the meaning is pretty clear here.
He got left by his wife/girlfriend and he now hangs around in bars at night, having sex with strangers.
Because it doesn't matter when you have nothing else.
It mocks the real emptiness of many people's lifestyle. Although they have beer and sex, which many men who don't get those want, they're actually only doing it because they have nothing else.
I think the meaning is pretty clear here. He got left by his wife/girlfriend and he now hangs around in bars at night, having sex with strangers. Because it doesn't matter when you have nothing else. It mocks the real emptiness of many people's lifestyle. Although they have beer and sex, which many men who don't get those want, they're actually only doing it because they have nothing else.