This is a Valentine's Day card. So it's flat, it doesn't have a fold. You write on the back, just like you did in 4th grade. It's 4x6 with the option of a red or white envelope. 

As much as I fear the Demogorgon, I can't help but feel for him. He seems like the Gollum of The Upside Down (I HAVE a theory concerning THIS... kind of). That said, the idea for this card popped into my head and it wouldn't leave. I'm not suggesting you're a Demogorgan if you gift this to your lover. Just go with it, K?