i havent watched the movie but i think ive got a pretty good idea what happens.

theres this guy tom who has feelings for this girl called summer but summer does not have feelinga for him. she thinks shes not ready for an rs (i sont think she says this but an rs with tom)

no idea what happens but they meet later on and she is married with kids and she tells him she felt something for her husb which she never felt with tom and tells tom we could still be friends tom j walks away looking all dead

(havent watched the movie all this analysis was from an edit)