Why did humans invent marriage and monogomy?

[Onecirrus]

I'm curious why one day out of the blue, this group of primates decided "Unleashing our sexuality is bad unless under certain very specific terms and conditions and if you don't abide by these terms and conditions the creator of the universe will hate you!" What was wrong with the previous system? Why does stage blue deny itself when not denying itself worked for hundreds of thousands of years?

I guess the deeper question here is, why did humanity evolve out of stage-red? What prompted such a radical change all of a sudden?

[SgtPepper]

Because societies that practiced monogamy faired better than other societies. 

Edited July 11, 2021 by SgtPepper

[Arcangelo]

Survival.

[Gianna]

Because once upon a time society treated women as objects to own. How do you take your living object off of the market? How do you make sure no other man sleeps with or sells your woman? By creating marriage. Of course, this is only one interpretation  

Edited July 12, 2021 by Gianna