How does my girlfriend not make enough money for groceries?

I wanted to keep it anonymous because this is about my girlfriend. I’ve asked her why she can’t afford groceries when her income is well above minimum wage and she’s single. She tries to explain expenses and whatnot but I’ve got even less money coming in than her and I make enough to buy groceries and not be broke. I’ve asked her why she can’t make it work on her own and she says it’s not that easy. I still don’t understand what she means.