Warning: contains spoilers for Amazing Spider-Man #89!
Marvel has finally admitted that Spider-Man's relationship with Mary Jane is toxic, and Peter Parker is better off without her and should begin a relationship with another - much better - character. Arguably the most successful superhero Stan Lee has ever created, Spider-Man's appeal is due to his real-world problems influencing his superhero duties and vice versa. As such, Peter and Mary Jane's relationship appears to be constantly on the rocks - but Amazing Spider-Man #89 provides a possible solution: break up the relationship in favor of one with Black Cat.
In current comics continuity, Peter is recovering in the hospital after surviving a deadly attack from the U-Foes. Suffering from radiation poisoning, Peter Parker's powers have waned after staying in a hospital bed for an extended period of time. Eager to return to his duties as Spider-Man (even as his clone Ben Reilly is swinging through New York as the new Spider-Man), Peter engages in regular nightly training sessions with Captain America and Black Cat. Finally, Felicity arrives in Peter's hospital room with a proposition.
Black Cat is ready to begin another training session when the news reports the arrival of a new villain in the city. Spider-Man naturally wants to fight, but Black Cat firmly disagrees: Peter hasn't been in the field in quite a while. Faced with the normally-determined Parker, Black Cat drops Spider-Man's webshooters on a nearby table - and uses them on Parker, attaching him to the bed. "Enjoy the show on the news or meet me at the Bugle...if you can!" shouts Black Cat before disappearing from view.
Mary Jane's response to the similar situation would not be a choice. Black Cat understands the need for Peter to be a hero - but she's also not reckless enough to allow Parker to suit up as Spider-Man while he's recovering. Thus, a test of strength is in order. This proves that Black Cat, despite her thrill-seeking nature, is actually far more mature than Mary Jane (who usually has her own interests in mind before Peter's, not to mention the safety of civilians and/or the city).
Marvel has established that Black Cat's only major flaw in a potential relationship with Peter is the fact that she likes Spider-Man far more than Peter's actual "face." But Spider-Man is a part of Peter, and Black Cat has the potential to grow as a character and balance power with responsibility. Mary Jane, by contrast, is seemingly incapable of growth - and so long as he stays be her side, so is Spider-Man.