A glimpse of current literature regarding the benefits of monogamy:

Effects on adults

What Do We Know About the Link Between Marriage and Health? Journal of Family Issues 31(8):1019-1040, 2010:

§  “Marriage reduces depression”
§  “Unmarried adults are more likely to drink, use marijuana, and drive recklessly”
§  “Married men and women experience lower mortality at every age relative to those who remain unmarried or lose their spouse through widowhood or divorce”
§  “A number of rigorous studies reveal that marriage can also lead to better general physical health and better outcomes for some specific health conditions, including arthritis, hypertension, and heart disease”

The impact of polygamy on women’s mental health: a systematic review | Epidemiology and Psychiatric Sciences 22(1):47-62, 2013

“Individual studies report a higher prevalence of somatization, depression, anxiety, hostility, psychoticism and psychiatric disorder in polygynous wives as well as reduced life and marital satisfaction, problematic family functioning and low self-esteem.”
 

 Effects on children

Parental Divorce or Death During Childhood and Adolescence. The Journal of Nervous and Mental Disease 204(9):678-695, 2016:

“Participants reporting a history of parental divorce present a significantly higher prevalence of psychiatric disorders, particularly alcohol and drug use disorders compared with control subjects. While participants experiencing the death of a parent reported a poorer overall health, the prevalence of psychiatric disorder after 17 years of age was not significantly higher than that of the control subjects.”

The consequences of fatherlessness:

“Children from fatherless homes are more likely to be poor, become involved in drug and alcohol abuse, drop out of school, and suffer from health and emotional problems. Boys are more likely to become involved in crime, and girls are more likely to become pregnant as teens.”

Economic benefits

Marriage and divorce’s impact on wealth. Journal of Sociology 41(4):406-424, 2005:

“Married respondents experience per person net worth increases of 77 percent over single respondents. Additionally, their wealth increases on average 16 percent for each year of marriage. Divorced respondents’ wealth starts falling four years before divorce and they experience an average wealth drop of 77 percent.”