Try playing with traits activated. With the exception of one trait (Relaxed), each trait unlocks to help you get a different end. In other words, if you reach a certain end because your affection is low, then you will unlock the affectionate for use if future playthroughs.
Another hint is that there are 2 stats each route that are important for determining the end you receive. The character chosen as Emma's significant other also affects the stats a little.
Good Luck!