This question is predicated on two assumptions - 1. that there were "homosexual people" (or for that matter, heterosexual people) in the middle ages, and 2. that "it" - meaning homosexuality - was "so frowned upon." Both assumptions are anachronistic and limited, at best.
The idea that one's sexual orientation was a central tenet of identity is a thoroughly modern concept. Before the mid-late 19th century same-sex behavior was something that a person just did without necessarily having an impact on their individual identity. Because sexuality was not tied to identity the way the way it is now, the modern understandings of the "wrongness" of homosexuality just doesn't stand up when you go back further in history. When we remove the homo/hetero dichotomy as a framework, everything else that we use to understand "homosexuality" falls apart under the weight of anachronism. Even the idea of needing a Grindr-like tool to locate other homosexuals is predicated on the notion that same-sex desire is "other" and needs to be hidden. "Cruising" and its elaborate etiquette of subtle cues, which has only just begun to be partially usurped by tools like Grindr, was created out of a need to hide in plain sight.
Essentially so much has changed about how we situate and understand human sexuality, that it becomes impossible to speak about anything beyond the very recent past without dramatically shifting one's framework of understanding.
This doesn't apply to Europe but Japan (so it might or might not be helpful, depending on how detailed you want your answer) - in medieval Japan, pederast relationships (relationships between samurai and their 'squires' - a homosexual relationship) existed (read: not common, but existed). In most homosexual-related articles of medieval Japan it is not presented as something that happened often.
Homosexuality has always been legal in Japan and there are no recorded punishments for homosexuality, so it would be safe to conclude that this would not have been an issue raised in feudal Japan.
The interesting thing about this is that (and this has been inside /u/cephalopodie's answer as well) in pre-modern times homosexuality was never frowned upon - most of the time, you just did it. You didn't talk about it, it wasn't publicised, and so most of the time there was neither disdain nor approval of it.
Sources:
Male Colors - Leupp, G.
kind of a similar question
http://www.reddit.com/r/AskHistorians/comments/2pg5mg/what_was_gay_life_like_in_medieval_europe/