Does the word "endogeneity" mean nothing to you? The sentence you cite is in no way an argument in favor of marriage. Maybe getting married, all else equal, will make one healthier. Or, perhaps, those who are healthier are both more inclined to get married and more attractive to potential spouses.

Endogeneity. Got it. I see what you mean. If I had to come down on either side, I would--I think--be more inclined to say that those who are healthier are more inclined to get married (and probably be more attractive to potential spouses). That would make such people endogenous. But, of course, because modern science is probably not capable of measuring such a thing, it does not really exist. Yet, what folks used to call endogamy (marrying into one’s tribe), was thought to be the only true gamete (marriage) because of the potential of actually knowing the other was the necessary condition of health and happiness; and one could not know an individual to the exclusion of the tribe (which is what defined the individual--as we might say--man or woman).