[THIS ARTICLE CONTAINS SPOILERS FOR SPIDER-MAN: HOMECOMING]
Every previous iteration of Spider-Man has been able to keep his superhero secret from his Aunt May, but Marvel sought to shake things up by having Marisa Tomei's May find out that Peter Parker was Spider-Man by the end of Spider-Man: Homecoming. Apparently, Aunt May finding out was something that Kevin Feige had been planning back when he was working on Sam Raimi's Spider-Man 2.
Talking to CinemaBlend, Feige reveals:
"J. Michael Straczynski did an issue when he was doing his run of Spidey many years ago where she discovered the secret. I think it was in the laundry or something, and they had a sit-down scene. And probably going back to Spider-Man 2, I would sort of carry that issue around and go, ‘We should do this someday, we should do this someday.' And it was great luck that it hadn't been done yet. That was always part of the plan."
As for the reveal, Feige says that May knowing Peter's identity will "force [Marvel] to do something unique." Apparently, Feige wanted this new Spidey to stray away from the "secret identity" route since that's something we've seen from all the other Spider-Men.
Come to think of it, only very few heroes in the MCU have secret identities. The only one I can think of as of now is Ant-Man, and since he was incarcerated in Civil War, it's very likely that the government already knows who he is.
For now we can catch the brand new Peter Parker in Spider-Man: Homecoming which is currently in theaters.