Either she's his girlfriend and he's just a complete asshole, or she's his girlfriend and he's being a sarcastic jackass(this is the only "good" scenario), or she's a clingy type who calls herself his girlfriend even though he's not into her at all and he's either set boundaries she ignores or he just doesn't really care if she invades his space like that.
Maybe their relationship is fueled, in part, by sarcasm and thats just part of their dynamic. By being sarcastic, he's actually demonstrated that his battery has recharged.