And I still won't regret it
Because you don't understand when she makes that face and you just can't help but kiss her and she's kissing you back and you're thinking things you really shouldn't be thinking about someone who's not really your girlfriend that you can't tell her in case it freaks her out.
Or maybe you do understand that and that's why you stayed with him even when he hurt you. Maybe this is what it's all about.
