Based on this reddit comment.
Quoting here:
If there were even 2 single young men coming back for every 3 single young women, it would necessitate young women to be extra competitive in the dating scene (i.e., compliant to a potential spouse). It's not lost on me that in the 1930's and '40's, there was lots of witty back and forth on screen between men and women. Late 1940's and '50's produced the blonde bimbo and June Cleaver.
My own impression is that America didn't lose anywhere near enough men for this to be a causal factor.
In America, no, not really. US death rates compared to the population of military-aged men were not very extreme.
The USSR, on the other hand, had drastically heavy casualties, especially among young men. The casualty figures are sometimes disputed, but it is safe to say that the Soviets lost more men than all the other combatants in Europe combined. This certainly had an effect on demographics - the cohort of men born in 1923 were the hardest hit, with only about 20% of them making it into 1946 without becoming casualties of some sort (wounded or dead). Also keep in mind that the USSR had its own share of troubles before the war which also contributed to losses in this generation.
After the war, it was rather quietly accepted for men to have mistresses besides their wives, and for women to be single mothers - there really were not enough eligible men for every woman to end up happily married.