sometimes something being heterosexual in themes is needed for the story that is being told and i think is important in order to create a proper ecosystem of queer narrative.
by this i mean the problem with straight fiction is often that it doesn't consider itself straight, it simply is. by contrast queer is a choice (the old classic "straight, white, able-bodied, cis, peri, man" is a universal story, whereas anything else is specific to That Demographic).
it's important to read heterosexuality, because it's saying something specific about society. deconstructing universality (again, similar to any other of those above-mentioned so-called "universal" traits) makes heterosexuality and heteronormativity (not the same thing) a thematic choice that interacts with queerness more authentically than if one simply slots man a into man b (as it were).
it's also interesting because a lot of analysis that decouples from heterosexuality on this here webbed site, does so in a way that -- as many have said before and will again -- handily also tends to remove women and people of colour and queer people who aren't gay cis men. it's not really interrogating text, it's merely substituting one form of universality with another without changing the core biases of said text (substituting heteronormativity with homonormativity).
when i read characters and/or themes as heterosexual, it's because those themes have relevance to the text and i want to highlight them (even if said text thinks that they're universal). yes, sometimes a text isn't aware that it's making things queer, but sometimes fans have a tendency to make things gay (not necessarily queer) that aren't doing the text justice.
examples include:
an angry straight man isn't necessarily or lbr primarily angry because he's secretly queer, but because straight men are socially raised to make anger a dominant emotion, burying other more healthy expressions and feelings. a storyline about that experience is interesting because he's straight.
a man and a woman being in a relationship isn't necessarily less interesting than two men in a relationship, and in fact the canon version may have way more substance than the one in which he leaves her (and she's angry but then accepts it every time) for a man. a storyline about this relationship is interesting because it may be challenging or modelling or deconstructing or playing with or simply presenting.
a man and a woman who have broken up isn't necessarily more interesting to read from the perspective of him having buried queer feelings that lead to [being a bad partner/being incompatible/outside forces making it the wrong time/etc], but can uncover a lot about heteronormative (AND amatonormative) cultural ideas about what a relationship "should be like" and how one can be more healthy in decoupling (ha) from those norms.
and also, these are interesting because of women. the angry straight man and his inability to emotionally connect with his partner leads them to break up says a lot about her role (and no, the narrative in question may not always be interested in her, but i can be) and how she exists in society and maybe also her flaws (is she someone who always wants to "fix" men? is she also holding onto toxic ideas about what a real man "should be"? does she not believe in better for herself? is she also angry all the time? does she want the relationship to fail? etcetc).
im not immune to "this makes no sense, gay be upon ye (regardless of gender jean harlow and myrna loy in libeled lady pls i believe you can do better)" but sometimes it does actually make sense and it's not sentencing a character to the straight salt mines of disinterest
also also, im always interested in how this interacts with queerness. are there queer characters in the thing? if not, where would they be? are there parts of the story that do read as queerer than intended and how do these clash with heterosexuality and heteronormativity in the text?
(couple of movies off the top of my head that seem cognisant of their heteronormative deconstructions, stepford wives, gone girl, daisies, fight club, american psycho....... (and yes we can discuss how these last two are very popular with a certain guy who thinks they're cool)) (maybe i need another list)