I ask this as someone who's writing what you might call an historical fiction. one of the scenes involve the main characters taking part in tavern banter with eachother about their sexual exploits like men are fond of doing, but as i wrote it i realized something- This is conservative, catholic medieval Europe. Would young men even have had the opportunity to "hook up" with women their age like modern men do?
Virginity before marriage was still considered a social virtue and i imagine the low status of women compared to their male counterparts would have made the unsanctioned socializing to even meet difficult. Is there any historical evidence that young people from the time period where so often secretly rustling each others jimmies that the hypothetical banter i'm writing on could have actually taken place?,or was it so taboo that only social outcasts like prostitutes could engage in it?
Yes, we have plenty of evidence for sex outside (before, during, after, or because of impossible) marriage from the late Middle Ages. Two important factors governing the dynamics are location within Europe and social class. In general, noble women tended to marry younger than noble men across the west, although noblewomen's age at first marriage varied perhaps the widest in the various location-class combinations. The urban artisan and laborer classes, and the rural peasants from which many of those laborers came, are where things get interesting.
Towards the Mediterranean--Iberia, southern France, and especially Italy--women in cities tended to marry (be married off) very young, in their early teens, while men marry very later--upper 20s or even early 30s. In northwest Europe--England, northern France, the Low Countries, parts of Germany--the so called European Marriage Pattern had begun to take hold in the 14th century. This is characterized by a relatively equal and late marriage age for women and men alike, in their late teens or early/mid 20s. These people would spend their adolescence working to earn money to make an attractive marriage partner, since marriage was in large part about setting up a household--but they'd also be on the lookout for potential partners during this time.
Some of the evidence for the thriving hookup and/or dating (it's not always clear) culture of the late Middle Ages comes directly out of that social pattern, in fact. Masters sue their apprentices for misbehavior or apprentices sue their masters for withholding wages for that cause, and the court records show that perceived/rumored lechery or going with some girl that the master did not approve of was a major source of strife. (Masters often wanted to be involved in making a marriage match for their apprentices, especially because artisans tended to marry within their own trade).
There were also plenty of cases where marriage could never be in the picture. The most obvious and ubiquitous case is clergy, especially but not limited to parish priests. (Alexander Murray discusses a tragic case of a monk who had managed to keep an unofficial wife and family on the side, but when confronted by his abbot and forced to stop seeing them, the monk killed himself rather than face life without them or without his religious order). There's been a LOT of research in the past 20 or so years on clerical "unmarriage"--how utterly common and generally accepted it was on a day-to-day basis. There's plenty of anticlerical polemic on this topic--priests' "wives" come in for all the slut-shaming--but examinations of actual court records show over and over that it's never a legal matter unless the priest upsets the locals in some other way, in which it's usually an excuse for action. Priests' sons even tended to follow their fathers into the priesthood! Canon law forbade this, but it was apparently the easiest thing in the world to win a "special" dispensation from the local bishop.
Another case of sex outside marriage would be across religious lines. In multiconfessional environments like parts of Iberia (Christians, Muslims, Jews) and various continental cities (Christians, Jews, but note if you're writing about England that England expelled its Jewish population in 1290), the typical situation was that the legal leaders of all religions banned their own women from having sex with men from other religions, but generally cared very much less about what men did. A major exception is a couple of Church rulings from the Crusader states, which come down harshly on miscegenation in all directions. Now, it's very important when dealing with medieval law to realize that a legal ban on something does NOT mean it was necessarily happening! (The medieval Church invented entire heresies and heretical movements when it suited them). However, there is pretty solid evidence from Christian, Jewish, and Muslim* courts in the late Middle Ages that interreligious sex and long-term relationships were happening. Most convincing are the cases involving children and inheritance, where no one is disputing the parentage of the children, just whether they are rightly members of one community or another (like when a Jewish man had two children with his servant--one before she converted to Judaism from Islam, and one after).
My favorite evidence for the ubiquity of medieval sex beyond marriage, however, is the crime of fornication in canon (Church) law. Fornication is sex between people who aren't married; prostitution and adultery are separate offenses. And fornication is one of the most common crimes brought before local canon courts.
What makes this evidence so compelling for medieval sex practices? Well, for assorted theological excuses and in large part because the Church wished to wrest control over marriage away from the secular nobility (the Church is the biggest single landholder in medieval Europe and a transnational political power; the stakes were enormous), a valid marriage between a woman and a man required...consent. Period. Not consummation, not the reading of the bans, not consecration by a priest. Consent. Priests hastened to clarify that this was not a licit marriage without the other elements, you might get some light punishment, but it was a real marriage.
Yeah, "we're actually married" isn't as common a defense for fornication as you might think. There also seems to be a legal distinction between fornication and concubinage, suggesting the difference between hookups or FWB and longer term relationships (like a priest and his "unwife").
Finally, one detail you could use to add some texture to the bragging that I just love. When men and women were contemplating marriage or when their families/guardians were contemplating marriage for them, an important part of establishing the betrothal and partnership--not to mention the rituals surrounding marriage--was gift exchange. Although dowry with marriage is the biggest focus of study, apparently courting a woman/woman's family often involved gifts to her and her family to show that the potential husband would be a good economic match.
Why this matters here is that profane (non-religious) poems and songs like to use this idea of gift exchange occuring in never-marital relationships. Generally there's some class prejudice and slut shaming involved--women are just in it for the sugar daddy--but the basis in actual pre-marriage rituals along with the medieval status of marriage as fundamentally economic lend credence to the idea that couples did exchange tokens as a sign of affection and going together--a lot like today. You're the author, you decide how to work this information in. It's just a cool detail that helps bring the topic to life for me.
If you're interested in reading a little more, there are two books I'd recommend here: