I think there is going to be a major surprise next week regarding Snape (he is a good guy) and Lily in book 7, but not necessarily that they were in love, but maybe?
I just finished re-reading HBP. Lily was loved by everybody and even better at potions than Snape. (Per Slughorn) Voldemort was not even going to kill her if she would just step away from Harry. (Yep..believe it or not...its there) but he zapped James without a second thought.
It seems the only time Snape really goes crazy is when its suggested in any way that he’s a coward. (How significant is this?)
Dubbledore was just about to reveal something to Harry about Snape when they were leaving to go after the fake horcrux. Something extremely significant happened to convince Dumbledore Snape was sorry and on their side, I just can’t even guess what. (Being in love with Lily just doesn’t seem significant enough.)
Only a week to go.....
;D
IMHO, very significant.