What is this letter about?

My Crush

Say it before the moment passes.

Friendship

Bench partners, forever.

Anniversary

One more year of us.

Birthday

Better than a forwarded sticker.

Missing Someone

Distance, in ink.

I'm Sorry

Some sorries need paper.

Thank You

For everything, quietly.

Proposal

Ask the old-fashioned way.

Long Distance

Miles, folded small.

Just Because

No reason. That's the reason.

Old School Friend

Last bench reunion.