The friend is jealous of the MC.
Talks with him and declares his love for the FMC.
The MC (who has been shown to be the nicest dude in existence) feels bad and extremely conflicted.
Just so happens to die in a traffic accident after talking with blonde dude (which, by the way, is the most common thing they say when someone actually commits suicide and nobody knows it was suicide until much later in time).
It is also a common trend in manga when you have a super nice MC who actually thinks more about others and has low self esteem (despite normally showing a cheerful front) to end up putting those others' feelings before theirs, and then commit suicide to clear the way because they can't cope with the situation.