I think it's quite simply about a man who's with somebody that he finds difficult to love, but he stays with her out of convenience. And the song is basically his admission to the girl that he's an asshole and that he can't really love the girl, because he can't keep up with her irrational emotions (her "insanity"). But he will act like he loves her, act like he has "the infection", which he feels is a sign of weakness. I think that he isn't able to get out of the relationship because he's too apathetic to break up with the girl, and yet too tired to actively stay in love, hence "I accept my fate".
I think it's quite simply about a man who's with somebody that he finds difficult to love, but he stays with her out of convenience. And the song is basically his admission to the girl that he's an asshole and that he can't really love the girl, because he can't keep up with her irrational emotions (her "insanity"). But he will act like he loves her, act like he has "the infection", which he feels is a sign of weakness. I think that he isn't able to get out of the relationship because he's too apathetic to break up with the girl, and yet too tired to actively stay in love, hence "I accept my fate".