We all know of the USSR's devastating losses during WWII, and we know those losses were mostly men between 20 and 40 years of age. I've heard that around 60% of Russian men in that age range were killed, which seems high, but even 20 or 30% would be a huge demographic hole.
That leaves a lot of women in that age range without a partner for a monogamous relationship. I assume repopulation was a hot topic right after the war. Russia's traditionally been pretty conservative, might this have been a chance for a looser approach to sexuality to become pervasive?
More broadly, I'm looking for any info on the war's influence on sexuality in the USSR.
So while I don't have specific statistics on hand to illustrate that the average number of partners increased from X to Y, we can say with certainty that men were encouraged to help so called "war widows" - a term used not simply for women who lost husbands, but women in the age range where a significant enough portion of the men were killed off as to seriously reduce prospects of finding a husband - have children.
Soviet propaganda campaigns to encourage motherhood predated the war even, but the massive calamity of course kicked it into overdrive. Various "carrots" existed, such as awards for bearing a certain number of children and various state assistance program, while legal "sticks", most especially the Family Law of 1944, limited abortion and increasingly penalized divorce. The shortage of men also meant a very important shift, in which the Soviets worked to try and both destigmatize single-motherhood by increasing state benefits they could receive and featuring mothers of ambiguous marital status in propaganda, while also tacitly encourage even married men to sleep around by preventing the single mothers from suing the father for child support. The result being that many men would have numerous affairs, and even unmarried men would often bounce from relationship to relationship.
Of course, it is also worth nothing that the aformentioned carrots weren't always effective. Illegal, underground abortions weren't uncommon, and divorce rates nevertheless rose through the decade after WWII despite the legal barriers and financial disincentives. And while the propaganda machine continued to trumpet motherhood as "a 'sacred duty' to the state", a common complaint, especially of single women who tried to balance a career alongside motherhood, was that the actual offerings by the state in support often fell very short of what was promised.
So anyways, to sum it up, yes, the Soviet authorities absolutely were trying to encourage people to have more children, and part of the means by which they did so definitely helped to encourage men, whether married or not, to be promiscuous.
ETA: Doing some digging and found some hard stats:
The 1944 legislation certainly resulted in an increase in the number of extra-marital children in the U.S.S.R. It is estimated that there were approximately five and a half million extra-marital children under eighteen years of age in the U.S.S.R. in 1957, and a peak of over six million in 1962, when there were approximately five million unmarried mothers. Part of this increase would, of course, be accounted for by the over-all increase in the population, especially in the non-Russian Republics.
Bucher, Greta. 2000. Struggling to survive: Soviet women in the postwar years. Journal of Women's History 12, (1) (Spring): 137-159,
Stone, O. M. "The New Fundamental Principles of Soviet Family Law and Their Social Background." The International and Comparative Law Quarterly 18, no. 2 (1969): 392-423.