There's a point to where the character is not really needed anymore. When you have a large cast that has expanded to where it is now from the past 60 years you get to where some characters are no longer needed to be around for the main character to grow and tell a good/decent story May Parker has outlived the usefulness of being a contributing character, Outside the recent appearance with Doc Ock in beyond there isn't much she can do and should be allowed to be let go in a meaningful way. Because she has been killed off in multiple forms of media has shown yes there is a time to move in and let Peter grow and learn again from this experience