This is all true for the nobility, the common people were less sexually strict on average.
The church had a big problem with the public bathhouses in the day, not only were males and females bathing together, bathhouses were also often brothels, gambling halls and taverns at the same time.
In the wake of the Hussite reformation there were also some other weirdo cults that sprung up, like the Adamites who celebrated mass in "paradisic nudity", they were too radical for the Hussites and were wiped out.
This is correct, but I wasn't attempting to imply the PEASANTS were necessarily always prudish or saintly, but I still think even the peasants would still have arranged marriages just because making the next generation was critical, since getting behind on things, and being an old couple with no kids made you a dead weight on the town, and NOBODY wanted that since people felt this greater then. Doesn't mean brothels and other shit couldn't happen, or that everyone did this persay, but my point was it was of a GREATER social focus to have children and raise them. If a man could do that and still visited a brothel, sure, maybe it was frowned on if known, but if he kept his family cared for, this was otherwise tolerated, since his "duty" as a man was being done. The real element of crime was more about not raising kids / abandoning them.
Infact since many peasants were seen as psudo property under lords and kings, its sensible that they would be invested in them breeding too, just so a kings son would have another generation of peasants to lord over. So forced marriages could even be arranged BY the king / lord. "hey, heres a girl from the next town over, make babies so your son can make crops for my son in 20 years. NO, this isn't a choice, do it or ill FUCKING KILL YOU".
So you aren't wrong, they definitely had brothels, hookups, infidelity, sex out of wedlock, rapes, ect, but as far as CHILDBIRTH went, society was framed with responsibility towards it even more than now. There was no CPS back then, so it was intense social pressure since fatherless children / lack of children was a MUCH nastier issue for the time. Its one of the reasons rapes lead into forced weddings, many wrongly believe it was a "reward" for the man, when it was actually more like a "you break it, you buy it" policy. Knocked a woman up? either your life is serving her, caring for her and raising her kid now OR....we will lynch you in the worst possible ways. It was EFFECTIVELY an easy remedy to prevent bastard children with no man around to care for them, if you force a marriage under the point of a sword.
its also why the church was big, since it effectively functioned ALSO as an orphanage in many cases in situations where fatherless children did become an issue, but the biggest bullwark against it breaking down society was intense social pressure, ALSO provided by the church. Definitely didn't work 100% of the time, but worked ENOUGH to keep shit from crumbling.