If you’ve read my work on this site or listened to my podcast Geeks Coast to Coast, you probably have realized that Kitty Pryde is my favorite comics 
Especially in the Ultimate Universe, Spider-Man and Kitty Pryde have very few friends their age. Spider-Man is friends with and occasionally teams up with Human Torch, but he is off on crazy adventures with the Fantastic Four or dating supermodels and actress to spend much time with Peter. When he started dating Kitty, Peter was also estranged from his best friend Mary-Jane, who he broke up with after she disobeyed him and was almost killed by the Green Goblin. Kitty is even more isolated. Most of the X-Men see her as their kid sister, and she has a complicated relationship with the X-Men her own age after Iceman kissed her to make Rogue jealous. At this point in their superhero careers, Kitty and Peter are very compatible. They need someone who they don’t have a complicated personal history with to talk with and maybe have some fun. This is why, after the initial awkward phone conversation, Kitty and Peter hit it off at their mall date in Ultimate Spider-Man Annual #1. (She says that when mutants take over the Earth, she will make sure the person who invented corn dog on a stick will be spared.)
Especially in Ultimate Spider-Man Annual #1, Kitty and Peter share a lot of great Brian Michael Bendis scripted dialogue. Spider-Man is a hero known for her quips and jokes, and Kitty can hold her own in the banter and phasing through Shocker’s gadgets department. They also share a love for science and pop culture ending their first date with a bit of dialogue from Raiders of the Lost Ark. However, Ultimate Mary-Jane is also witty and intelligent and runs the school’s TV channel. But she doesn’t understand what it’s like to have superpowers, a secret identity, or fight crime. Kitty can help Peter in his mission to make sure that what happened to his Uncle Ben doesn’t happen again. They help rescue the X-Men from Deadpool and the Reavers in Ultimate Spider-Man #91-94, and Kitty even begins wearing a costume so they can go on normal dates as Peter Parker and Kitty Pryde. Kitty wants to protect Spider-Man’s secret identity so much that she even asks Professor X to wipe Aunt May’s memory when she finds out he is Spider-Man after the “Ultimate Clone Saga”. Kitty is someone who can help Spider-Man beat the bad guys while also helping him deal with keeping his gifts secret from the people around. Peter can also empathize with Kitty being left out by the X-Men as he is looked down on by more “adult” heroes, like Daredevil and the Ultimates.
For a few years in the Ultimate Universe, Kitty Pryde and Spider-Man were quite the cute couple swinging around New York and sneaking kisses after beating up Ringer, Shocker, or some ridiculous supervillain. However, because of Peter’s deep friendship with Mary-Jane, their relationship was never meant to last even though they were well-matched. But Bendis did a good job incorporating Kitty into subsequent Ultimate Spider-Man arcs by giving her the darker persona of Shroud that she used to fight crime in after using mutant powers were banned. In this persona, she rescued Mary-Jane by herself and helped Spider-Man protect Midtown High from the Spider-Slayer. Like much of the Ultimate Universe, Kitty Pryde was extremely traumatized and angered by Spider-Man’s death. However, I think that his heroic sacrifice and death spurred her on to re-form the X-Men underground with Iceman and Rogue in the new volume of Ultimate Comics X-Men and eventually found the settlement of Utopia.