Jacknifed

I am jacknifed in your diary
I may be home alone, I'm not lonely
And I'll be stronger when I'm stronger
I'm at my bleakest, at my weakest
I am worn out and I'm frustrated
I tried to work you out but you're a stranger
I've got the rulebook
it's missing pages
And I could guess but that's so dangerous
Turn around when you get to the coast
there's nothing there to see but sea
Leave those mountains left unclimbed
And put a line right through me