Well if it's not teenage angst,

bride/groom with cold feet?

At least if you have the Sinatra version in your head, not so bad.

unattainable or fleeting

Exist, exist one single lodge.

Safe but not out after first dodge.

(Show your work for full credit)

Well, this is all I can guess at so far

Exist - Be/B

One - A

Single - 1/l?

Wait, is it

Northward?

~ Samurai -> sword? ~

What was forbidden was

Knowledge - it was forbidden for them to eat the fruit of the tree of knowledge of good & evil

As tangible things go, it makes me think of a

library, or school/learning

pride/ego?

hmm, it also reminds me of

a kid's music box

I believe the rule is

Square it & add it.

2, 2^2, 2^2 +2, 3^3, 3^3 +3, 4^4, 4^4 +4, 5^5, 5^5 +5, 6^6, 6^6 +6, 7^7, 7^7 +7

your dreams

Admittedly this is not *quite* correct, but if you take into account some vernacular language it could also be Kinetic & Potential (energy) states.

And don't forget Plasma!