SPOILER WARNING: This article contains major spoilers for Amazing Spider-Man #800 by Dan Slott, Nick Bradshaw, Humberto Ramos, Giuseppe Camuncoli, Stuart Immonen, Marcos Martin, Victor Olazaba, Cam Smith, Wade von Grawbadger, Edgar Delgado, Java Tartaglia, Marte Gracia, Muntsa Vicente and VC’s Joe Caramagna, on sale now.
Throughout Dan Slott's astonishing Amazing Spider-Man run, there have been plenty of references to the tragedy that struck Peter Parker's relationship with Mary Jane Watson at the end of the infamous "One More Day" storyline (by J. Michael Straczynski and Joe Quesada), which occurred a little over a decade ago. The arc saw Peter Parker's Aunt May fatally injured as a result of Peter's decision to reveal his secret identity to the world prior to the first "Civil War." In the end, Parker and Mary Jane decided to strike a deal with Mephisto, who offered to save Aunt May in exchange for permission to erase Parker's marriage to Mary Jane.
It was said that the iconic marriage was erased in order to keep Peter Parker relatable to reader. This is why the two characters have been kept from reconciliation, though several writers have teased and seemingly built toward an end to their separation. Though once feasible, the relatability excuse has recently been effectively obliterated by the reception of similar such relationships in DC's comic line, particularly Superman and Lois Lane having a son, and Batman being poised to marry Catwoman. Relationships don't prevent characters from being relatable. In fact, they tend to have the opposite effect.
Someone at Marvel might have realized this in recent years, because despite the initial reasoning, there has been a clear effort to remind readers that Peter and MJ were once an iconic comic book couple. It's why Amazing Spider-Man (and occasionally other comics) keeps coming back to their relationship.
There was the "Renew Your Vows" miniseries, which in turn led to the current ongoing comic which explores the relationship that never happened in our reality. Then we have MJ's admission that she has always loved Peter at the end of "Dying Wish," her attempt to reconcile with Peter when the latter had been possessed by Doc Ock in Superior Spider-Man, and most recently, after she helped fend off a Hobgoblin attack at the end of "Threat Level: Red," she and Peter spent a night together, as implied by a scene that very clearly alluded to MJ's famous first appearance in Amazing Spider-Man #42 (written by Stan Lee, artwork by John Romita Sr.) in which she said her famous line, "face it, Tiger...you just hit the jackpot!"
The tense relationship the two once had after striking their deal with Mephisto has seemingly disappeared. They've grown closer once again, and constantly seem to be on the brink of getting back together. It's almost as if Slott has been subtly building toward the reunion fans have been dying to see for ten years now.