1/3 Okay, I'm going to start off by doing that obnoxious historian thing: spending a long time deconstructing the terms of the question. But I'l eventually give you a real answer, I promise. I'll put it below the ~~~ line break so you can skip ahead if you want.

The idea of "the West" is problematic, but I'm going to assume you mean Europe? Even narrowing our focus to Europe still leaves a lot of room for nuance, because we can't really speak about a meaningful "European" identity or culture prior to the 20th century/the Enlightenment/the Crusades/insert significant date here. But especially in the early medieval/late antique time period you've alluded to in your questions, there wasn't a whole lot of shared identity between, say, fishing villages on the western Iberian coast and farming communities in what is today Poland.

It's also hard to pin down what we mean by "homosexuality." Homosexuality is pretty clear to you and me in the 21st century, but the idea that your sexual behavior means something about who you are is a relatively recent development. (Historians love to argue about exactly how recent it is.) David Halperin has an analogy that's helpful for denaturalizing our current equation of sexual preference with personal identity. Halperin notes that some people prefer the white meat of chicken, and some dark meat. Some people like both about equally, some people will only eat white meat, some people don't eat chicken at all, etc. Those are all dietary preferences, analogous to sexual preferences. But we haven't decided, as a society, to divide people between white-meat-eaters and dark-meat-eaters. There is white-meat-eating behavior, but not white-meat-eating identity. (This behavior vs. identity thing is associated with Michel Foucault's interpretation of the history of sexuality, explained in his creatively titled The History of Sexuality.)

Another problem with talking about homosexuality is that the "homo" part of it is unstable. We typically think today of two predominant genders (and/or two predominant sexes) that are usually lifelong.* But that hasn't been true in all places and at all times. Moving out of "the West" and into the Asian part of Eurasia, Afsaneh Najmabadi and Gregory M. Pflugfelder have supplied fascinating accounts of age-contingent gender (or gender-adjacent) categories in Persia and Japan, respectively. In both these cultures, grown men were allowed to--and expected to--have romantic and sexual relationships with youths. When the youth began to grow a beard, he was expected to transition from being sexually penetrated by his older male partner to being a penetrator of a beardless youth.

*I see you, nonbinary, agender, and genderfluid friends. <3

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