I think this is a story of two "no strings attached" lovers who planned to split once summer was over, but they start to get legit feelings for each other.
'You said if you don't let it out you're gonna let it eat you away, I'd rather be a cannibal, baby'
This is referring to his attitude towards the relationship at the beginning, seeing it as just a fling.
'Put another 'x' on the calendar, summer's on it's deathbed'
They (or at least he) planned to end the relationship at the end of summer; summer's on it's deathbed i.e. summer is almost over.
'There is simply nothing worse than knowing how it ends'
There's no point guessing when or why the relationship will end, so just keep going and see what happens.
I think this is a story of two "no strings attached" lovers who planned to split once summer was over, but they start to get legit feelings for each other.
'You said if you don't let it out you're gonna let it eat you away, I'd rather be a cannibal, baby' This is referring to his attitude towards the relationship at the beginning, seeing it as just a fling.
'Put another 'x' on the calendar, summer's on it's deathbed' They (or at least he) planned to end the relationship at the end of summer; summer's on it's deathbed i.e. summer is almost over. 'There is simply nothing worse than knowing how it ends' There's no point guessing when or why the relationship will end, so just keep going and see what happens.
Just my small interpretation