Straight x Gay possible? (Pls give example)

You meant he grew in homophobic environment, assumed himself straight because of it... And bam! He discovers actually he's not?

Entirely possible.

That is... Not by all mean an easy task. I could say that you can use a setting where they are on a "same ground" (ah well I'm a s*cker at explaining things) and make the not gay guy "see and know" how the gay guy life is. Somewhat, but do know that if that person is someone who is very believing with their mindset that gay or LGBT in general is bad, it would be harder and time is really needed for him to understand, thought all of it might go on naught if they themselves did not want to change their mindset.

You don't have to use the gender pronouns to create a story.
It can be bromance, it can be non-sexual.
Just seeing your characters as human being is enough.

If the "straight" guy falls in love with a gay, then he is not straight. So it would be logically imposible.

He may be a LGTB person who is repressing his true sexual orientation.

There are cases of people who stayed in the closet too long and even married people of the opposite sex to pull out a facade of being straight. Those cases are particularly sad because, the wife feels used when she finds out and the gay is basically just pretending to love someone he doesn`t love.

I mean if he is sexually interested in the other person and wants to do physical stuff with him... the guy can no longer be considered straight. You pretty much have two options, either he discovers who he really is and can remain closeted due to the dangers of that time period, or he lives a life of denial

Wouldnt this be more of him being bisexual than straight then?

I'm under the belief that subconciously everyone's a little bit Bi so if one's less accepting and hiding themselves in the closet (like deep in there). It might be possible.

hey xtraordinary.
so a lotta people mentioned how its impossible but it is.. technically possible. people's sexualities are fluid, theoretically a guy who was straight for 30 years of life Could develop homoerotic/romantic feelings towards only one person one day, and if they still see themselves as straight because it's just this one dude, then.. i mean, yeah, they're straight. guess what? sexualities are self-given descriptors.
the thing about fiction is that it's fiction, and even a super unlikely kind of annoyingly-cliche scenario where an otherwise straight man falls for a gay guy isn't that uncommon and isn't theoretically impossible, just highly improbable and as mentioned before, kind of annoying because it undermines gay, bi, and pan sexualities.

let's talk about the olden times though, because you did step on a really common thing here
when homosexuality was illegal I'd say (not based on anything concrete, but I mean this is totally google-able) I'd assume most gay or bi people classified themselves as "straight but id go for that" because being gay was so dangerous and seen as detestable. and its important to remember that love comes in many many forms, and so does sexuality, with the right social pressue and base understanding, and general circumstances, a person who'd otherwise be seen as completely gay could totally see themselves as staight and feel real feelings towards women, and that's something to remember too. just because someone's gay, don't mean they can't love a woman, it's just in a different way and maybe they're forced to channel what would otherwise be a more platonic love into a weird mimic of sexual/romantic love.
the thing is though that the gay community was almost like a seperate society up till im gonna say the 90s? and even then... I think a lot of us don't really get to hear about that community and learn about it and what it was like, what were the social norms, what was commonpalce for a gay person who's actively identifying themselves (even if in secret) as gay during those times in history, instead getting this sort of (completely mistaken) view of history where 20 years ago gay people barely existed when, in fact, gay people were fucking living it up. and the thing is that it's very hard to find proper places to learn about these things from because they were so intertwined into the society at the time but not talked about in public, records were just not something kept that well and it's not always easy to find the context in which hearing someone talk about crazy sex & drug parties, but it's not impossible.
i guess what im getting at here is that your story concept is completely valid and there can be a lot of truth to it, if you want there to be (I mean honestly? you don't have to), but if you wanna touch on that subject you're gonna have to prepare youself to Really Dig In to some sweet, sweet research because there's a lot to be unconvered.
also this is like, a really fucking huge period of time. when are we talkng here pal? the 30s? 60s? there so much to go on here bud.

On a sidenote if you just wanna have some fun with easily accessible based-on-a-rea-story gay-romance content rooted in those time periods (and to be fair i dont watch a lot -by which i mean i barely watch any- but they're still good)
A Very English Scandal1 - Hugh Grant (i know right?) and Ben Whishaw (q from the new bond movies) play a very fun and fantatically written story about a politician and his ex-lover's ... complicated relationship. prepare for some politics, murder, and flamboyant drama. it's a 3 episode series which touches exactly on that "gay but identifies as straight" finer points
Kill Your Darlings - Daniel Radlcliffe (harry potter), Dane DeHaan (he did the green goblin that one time) and for some reason though im not complaining Michael C. Hall (dexter) with a large and overall really fantastic cast play Allen Ginsberg, Jack Kerouac and William Burroughs (yes, the poets) in a truly beautiful, dare i say masterpiece of a movie, with poetry, murder, homosexuality, and some really good cinematography. like, damn. it took me all of 2 seconds to fall in love with this film.
Risk1 - this isnt a movie but it's a podcast (its very nsfw so fair warning) which has peopel come on up and tell their true stories about life and everything small to big and it has a lot of truly great stories settled around the 70s, 80s, about the gay commnunity which are always great fun and if you have the patience to seek them out, they're always worth a listening to (hosted by kevin allison, yes that dude from the state)
edit: sidenote about this one yes i said the 80s but like i said earlier, its hard to find personal testimony stories without actively looking for them which i wasnt so. thats what i got, man

I don't have enough data on your characters to help you, but if you fall in love with someone who is the same sex as yourself, I'm pretty sure that means you're either gay or bisexual. Unless the straight guy has no sexual feelings for the gay guy, anyhow, and they're just really close--then that might mean they're just really good friends. But it sounds as if your straight guy maybe just thought he was straight because that's all he knew and that's what his society told him he was, but then he maybe discovered he wasn't so straight when he met this gay person? But anyway, by definition, I don't think you can be straight and then fall in love with a gay person, haha.

so the impression im getting is that your story is abt a man from The Old Days travelling to the modern day and falling in love with another man?

this is an interesting premise - it sounds to me like the most logical arc is that your MC realises, in the new openness of the modern world, that hes actually bi or gay, in some kind of self-discovery arc.

and to ask how someone who was extremely homophobic can fall in love with another man - well, it happens today! plenty of gay ppl grow up in extremely homophobic environments and have to unlearn all that when they enter into their new queer lives.

your character would likely have to go on quite a long and arduous journey to learn and un-learn before they can accept themselves, which can be both painful and joyous at the same time.

I have to say no, but hear me out. The very definition of being straight means you only fall in love and are attracted to the opposite gender. If he is falling in love with a boy, it means he was pansexual or bisexual though he never realised before he didn't meet the right guy.

Orientation is not an off and on switch. If he falls in love with girls and boys, he is not straight. Simple as that. And that's ok. I've met people like that, but even they admitted they were not straight after all.

Orientation isn't all or nothing, either. It's been known from time to time for someone who's 99.9% hetero to find that one person of the same sex they could go for. And as loath as some people are to hear it, a few people who are 99.9% gay find the one person of the opposite sex they could genuinely go for. It's highly unusual, but it has happened even to two or three people I know.

The waters are further muddied when you consider romantic attraction versus physical attraction. The two don't always go together and don't always match.