Possibly the most important and integral character to the Spider-Man universe, besides Spider-Man himself, is Aunt May. Aunt May raised Peter as if he were her own child, and is Peter's only living relative in most universes. She is loving, caring, and protective of her nephew, having been this ways since her very beginnings back in Amazing Fantasy #15.
Though Aunt May is a great support character, possibly the best in all of the Marvel universe, she unequivocally holds Peter Parker, and subsequently Spider-Man, back. Peter is a bit too reliant on Aunt May, and some fans believe that this is preventing the character from reaching his full potential
10 Peter has to take care of Aunt May — All the time
Aunt May's exact age isn't known but she ranges from 50 to about 70 years old, depending on the version. The comics and the MCU have been rather flexible with her age, adjusting it accordingly over the years— but regardless, in the early days of the Amazing Spider-Man comics, Aunt May was frail and old.
She always was getting sick and couldn't be without her nephew for more than a few hours. Spider-Man constantly worries about her health and spends half of his time looking out for her. She can't even step outside without Peter freaking out. Peter is a loving guy, but his dedication to Aunt May is a bit much at times.
9 He has to keep his Spider-Man identity a secret from her
The one person Peter Parker desperately wishes to reveal his secret to is his aunt. Though he has revealed his Spider-Man identity to her on multiple occasions in the comics, all of these instances have been retconned. If Aunt May knew of Peter's secret, then she would be an even greater support character. She could cover for Peter and provide some more emotional support.
Revealing his identity to her would take so much weight off of his shoulders. After so many years, it is a bit unrealistic and ridiculous that Aunt May still doesn't know of her nephew's secret crime fighting alter ego.
8 She has traumatized Peter on many occasions
The most infamous instance of Aunt May traumatizing Peter was during the Brand New Day era. During this time, Aunt May began a relationship with J. Jonah Jameson's father, John Jonah Jameson Sr. Coming home, Peter walks in on a very intimate moment between the two. The scene is both shocking and scarring to fans and Peter alike.
But besides this, she has also "died" multiple times in the comics and, more recently, has gotten cancer. Clearly, Aunt May has a life that is exhilarating in some versions and extremely difficult in others, but either way, it's not necessarily the most beneficial for her nephew and his ambitions.
7 Aunt May doesn't understand Peter as well as she thinks she does
As much as Aunt May loves Peter, she just doesn't understand Peter as well as she thinks she does. For one, he isn't this weak nerd who only spends his days taking photos and studying. Peter is more independent, more athletic, and smarter than she takes him for.
There is a disconnect between Peter and May. Early on in Nick Spencer's Spider-Man run, Peter has a conversation with Aunt May about his revoked PhD, the degree that Peter earned when Dr. Octavius was in Peter's body. Instead of trying to understand Peter and digging deeper into his situation, Aunt May assumes that he went down the wrong path, despite his good intentions. This has a negative effect on Peter, and subsequently Spider-Man, as he is inadvertently shamed for being a superhero.
6 She's been involved with villains before
Aunt May's been involved with many Spider-Man villains over the years, endangering herself and Spider-Man in the process. She's had a complicated history with Dr. Octopus, having rented out a room to him before and almost even marrying him. In more recent Spider-Man history, she volunteered at FEAST, which was run by Martin Li/Mr. Negative. When Peter, Aunt May, and Mary Jane were living in Stark Tower, she met Tracer and is almost killed.
May Parker's run ins with various villains makes Spider-Man's job that much harder, since it endangers her while simultaneously allowing villains to get closer to Spider-Man.
5 Spider-Man changed reality to save her life
In the events leading up to the notorious "One More Day" story, Aunt May convinces Peter to reveal his identity to the world. In doing so, Aunt May and his then wife Mary Jane are forced into hiding. An assassin, hired by Kingpin, then finds and shoots Aunt May.
In order to save her, Peter makes a deal with Mephisto, thus sacrificing his job, identity, and marriage for Aunt May. The Spider-Man mythos and character changed because of this— and not for the better in the view of many fans, who felt that it resulted in a character regression for Peter.
4 Aunt May Hated Spider-Man for a time
Despite her nature, May Parker didn't start off liking Spider-Man. Whether it was because of Dr. Octopus' influences or because she was too ignorant to actually do her research, May truly believed that Spider-Man was a villain. This wasn't exactly great for Peter as one of the most caring and impactful people in his life unknowingly thought the worst of him and would constantly tell him so.
Outside of fighting, Spider-Man is in a constant battle with the media's portrayal of his image. Knowing that these lies have worked, on Aunt May of all people, was a devastating blow for Peter.
3 Aunt May never lets Peter grow up
In the early days of the Amazing Spider-Man, Peter was in his high school/college student years and so it made sense that he lived at home with Aunt May. He was still young and broke. Fast forward to the more recent comics, Peter's older now but is still broke and still lives with Aunt May, making him a bit of a man-child.
Peter needs to break off and let Aunt May live her life. In other words, he needs to grow up a little. Although checking in on Aunt May is great, he's still practically that unemployed college kid from way back when. The only way to truly protect Aunt May, while simultaneously bettering himself, is to loosen some of the codependency of their relationship.
2 Aunt May reminds Peter of his parents
Peter never knew of his biological parents— CIA agents Richard and Mary Parker— as they died when we was still young. After they perished, Peter was raised by Richard's older brother Ben and his wife, May. Having only faint memories of his parents, Peter often equates Aunt May to his mother and father.
Though May and Ben have been great adoptive parents to him, he is constantly reminded of his orphan upbringings each time he interacts with Aunt May, since she is his only living relative. It's a hard pill to swallow, especially since Peter and his aunt are so close.
1 Aunt May Reminds Peter of Uncle Ben
Uncle Ben is perhaps the most influential person to Peter Parker, since his death represents Spider-Man's greatest failure. Failing to save his uncle, he makes Aunt May a widow. Peter can't afford to tell Aunt May because of what it would reveal, so he has to live in a state of constant agony.
Unlike seemingly everything else in comic books, Uncle Ben is actually dead and stays that way. In a promise to himself and his deceased uncle, he takes care of Aunt May. Thus, not tending to Aunt May would be breaking that promise, and that's something he is unwilling to do, even if it means causing numerous complications for his life as well as May's.