Turns out my Britishness got the better of me and I miscalculated the timeline of 'In The End' because of how the US schooling system works.
Soooo, I've been through and edited based on a reformed timeline so it should all make sense now.
For reference of current/future readers:
MASON AND LEXI ARE 20 YEARS OLD AND IN THEIR JUNIOR YEAR OF COLLEGE!
As a result the whole 'big betrayal/change' (whatever you wanna call it) was 7 years ago instead of 6 because it still happened when they were 13.
I hope it makes sense now!
If not, oh well - it's fiction so ya know deal with it.