Through the Middle Ages, homosexuality did not exist as a social concept, just the same as "heterosexuality" didn't. Today, many people think that homosexuals were harshly punished but recent studies show that this wasn't the case. Medieval people did not have concepts which would describe different types of sexuality (heterosexuality, bisexuality, heterosexuality and etc.) but they rather viewed it as a behaviour that's a kind of act that people could commit, like adultery. The other common mistake people make that there were harsh laws forbidding homosexuality in general. That wasn't the case, while the laws didn't exist and homosexuality (in general) wasn't banned, but was rather 'taboo' at the time and greatly looked down upon.
Some countries however did make punishments for people who have committed an act that's against the "Natural Order" and "Natural Law". Some of such punishments involved castration, dismemberment and finally murder. Such punishments were usually done and enforced by the Church and were more common in regions that had a strong influence of the Church.
In medieval times, sex was focused around a masculine figure and a man with a penis which was needed for sexual acts and by such lesbianism was also considered to be against "Natural Order" and "Natural Law". The first text found that speaks against the lesbianism and lesbian women was from St. Paul to the Romans: "women exchanged natural relations for unnatural, and the men likewise gave up natural relations with women and were consumed with passion for one another…and receiving in their own persons the due penalty for their error." While he didn't specifically mention "sex between women" and "lesbianism" as a concept he says that such unnatural acts will be punished at the end, presumably by God.
In the medieval ages, sexuality as a concept was divided into three other areas: Sex, Gender and Orientation. Sex: male / female. Gender: masculine / feminine. Orientation: men / women / both. People didn't believe that sexuality was a choice, but rather that it was inherited from someone's gender. A man was automatically assumed to be masculine and like women, while women were presumed to like men and be feminine. They had no concept of a "cis-gendered homosexual male", a homosexual male who behaved very masculinely. This is not to say that they would be "offended" by such a man, but rather that they would find it conceptually difficult to understand. If a knight was highly skilled at masculine behaviours such as warfare and martial prowess, many would dismiss the suggestion that he privately enjoyed having sex with men – following the familiar stereotype that "he is too butch to be interested in other men", etc. Figures throughout the kingdom that show that they are good in combat and show other common and accepted things that are considered to be "masculine" would never be suspected of being homosexual in private because of the things said above.
Similarly, people back then only perceived "male" and "female" as genders. If a male man acted femininely and didn't adhere to normal norms for masculine figures he would still be called "male" and wouldn't be registered as another gender, but rather a defective kind of 'male'. Also, a man couldn't have masculine behaviour nor be a true 'man' without a functional penis. Men that were castrated or dismembered were thought to automatically inherit feminine features and behaviour which was often seen in eunuchs.
In the text above, we see that homosexuality was often portrayed against "Natural Laws" and "Natural Order" but that many laws didn't specifically forbid it. People didn't have social concepts such as 'transgender' nor did they define sexuality other than being interested in males and females. People were thought to automatically inherit their characteristics based on their gender and as such people who didn't follow such characteristics were seen as different. However, that doesn't mean they were social outcasts but generally distrusted. During the 13th century, the Church actively started punishing homosexuality. Several historical figures are, today, thought to have had sexual relations with both men and women. In Ancient Rome for example, it was thought that having sex with another man gave oneself strength and power over others.