You realize it's brought up in movies all the time, except since they're usually straight, straight people don't care?

Straight couples exist in movies and it's perceived as normal. The relationship itself might be part of the storyline, but their sexuality itself is not relevant to the plot (but they're still shown as straight).

Let's think about Star Wars. If Princess Leia had been Prince Lee, the exact same plot points can happen across all three movies. Like, literally every single point. Some identifying words change (now he's Luke's brother, for example), but the story remains the same, because nothing about the sexuality of the characters is relevant to the plot. Han and Lee fall in love. Now you have two gay characters, and their sexuality is not relevant to the plot, just as their straightness was not relevant to the plot. The only thing that changes is the perception by the audience, because gayness is not viewed as the norm, and people feel that any deviation from the norm must be done for a reason. The reality is that gay people just exist, and exist as the same types of people as anyone else. There shouldn't need to be a reason a character is gay, and their gayness should not have to be relevant to the plot in order to justify them existing.