Well in the 13 Riders comic he did win the war though... so it's not like he's always fully screwed XD;
And how is dieing most of the time emo? Shinji isn't emo 0-O; When he's in doubt he always go and find the answer instead of sulking and try to cut himself.
I think the movie ends simply with Shiro resetting time again, since there's no point to continue the war if Yui died already, and that the two best friends essentially chose not to go as Shiro said they should but defend humanity.
It's just titled Ryuki because they need a single title character imo. Knight is as much as a main character as Ryuki is, and could easily be more prominent than Ryuki if Kobayashi chose to do so.