Possibly, it's a story that explores their friendship evolving into something more. Or it could focus on a specific event that changes their relationship in a profound way.
I've read a fanfic that takes the emotional depth of 'A Walk to Remember' and applies it to Kurt and Blaine's relationship. In this story, they face hardships like in the movie, but their love for each other and their passion for music help them get through. It has some really touching moments where their friendship and love are put to the test, much like in the movie.
You can start by looking on popular fanfic websites like Archive of Our Own (AO3). Just use the search terms 'A Walk to Remember' along with 'Glee', 'Kurt' and 'Blaine'. There are usually tags and filters you can use to narrow down your search further.
Definitely Mercedes. She could be the one who gives Kurt some great advice on love and marriage. Also, she might sing a beautiful song at the wedding. Artie would also be a great addition. He could be in charge of the music playlist for the reception. And Santana, she could be the sassy bridesmaid or groomsman who adds some spice and humor to the whole event.
I'm not sure if there is a specific 'glee kurt cheats on blaine fanfiction' that is considered 'worth reading'. Fanfiction can vary greatly in quality. Some might find such a plotline interesting because it adds a new layer of drama to the relationship between Kurt and Blaine. However, others might be turned off by it as it goes against the positive image of their relationship in the original show.
A popular fanfiction is 'Nine Years: A Kurt and Blaine Retrospective'. This fanfic is more of a collection of vignettes that look at different moments in their nine - year relationship. It's great because it allows the reader to dip in and out and still get a full sense of their journey together.
One popular one could be those that focus on their relationship development in high school. For example, stories might explore how they overcame the initial shyness and social pressures at McKinley High. Another type could be about their post - graduation adventures, like moving to New York together and facing new challenges in the big city.
One popular story could be 'A New Beginning for Kurt and Blaine'. It often focuses on their relationship development after certain events in the 'Glee' series. Another is 'Kurt and Blaine's Adventure in New York', which might explore their lives in the big city.
The main characters are Blaine and Kurt. Blaine is the one who is proposing, so he is likely to be very nervous yet determined in the story. He has planned this big moment and is ready to take their relationship to the next level.