Currently living without a partner and cohabitation and previous divorce increased the risk of accidents, violence and suicides. This indicates that also other mechanisms than immediate support from a partner are important in the formation of marital status differences in mortality.
That is from a new article in the Journal of Epidemiology & Community Health (). It has been documented that marriage makes people (more) risk averse, and as a consequence less likely to engage in life threatening activities. The classic article in economics is Akerlof (2001) - not available online.
There are academic advantages as well -- from a paper by Joseph Price:
Using data on 11,000 graduate students from 100 departments over a 20 year period, I test whether graduate student outcomes (graduation rates, time to degree, publication success, and initial job placement) differ based on a student’s gender and marital status. I find that married men have better outcomes across every measure than single men. Married women do no worse than single women on any measure and actually have more publishing success and complete their degree in less time. The outcomes of cohabiting students generally fall between those of single and married students.