Obviously, drinking gasoline incurs bodily harm on you, but also, being an accessory to that kind of behavior and having to decide — it incurs harm upon you, too. And then, are you responsible for permitting that? If you stay, are you responsible for permitting it? And if you leave, are you responsible for not intervening? If you intervene, are you out of your bounds? Everything about the song is figuring out how you should act in your level of responsibility for your own health and to others in the dynamic of a relationship, which is a difficult lesson to learn.
I feel like I would have put myself into an unfavorable or unhealthy position for this person and maybe recognizing from an outside perspective that that destructivism is a more healthy thing to do than to stay in it for the sort of, romantic, admirable belief that subjecting yourself to this kind of sacrificial, fatuous love would be more of the right thing to do.