The last panel makes it look like she liked him puking... Maybe she has that "I can fix him"-fetish xD
I agree that it's a bit weird, because personally I'd say that's "decay up".
But maybe we/she's wrong about what gives her MP? Or more exactly what takes it away?
Maybe MP goes up when she's generally enjoying things like some aloof godlike being. But when things get too "physical", she is knocked off that pedestal and becomes more "human".
(Either way I think the base for "puke = MP down" instead of up is because else this would become a very different manga when he has to get horribly drunk to help his wife..)