1) I know they were going for a "set up for a proposal" but it just looks, at a glance, like the window display is for a regular old pair of house keys. This is confusing. I genuinely expected the post-it to read, "Sorry for the mess, we've had a break-in and the thief tauntingly left the keys to the store behind."
2) The big set of keys kind of make the ring -- no slouch in the sparkly department -- look tiny in comparison. The reaction to this potential proposal set-up would be, I feel: "Ooooh, keys! -- Wait, look, a ring! Oh. It's kind of small. No, no -- I mean, it's nice. But not as big as these keys, you know?"
3) Wait, is this imaginary person proposing to SOMEONE THEY HAVE NOT YET SWAPPED KEYS WITH? This seems like a bad idea. Someone tell them they are rushing things!
4) Again, I don't mean to be so picky, but -- any important announcement/question: a break-up, a proposal, a firing, a declaration of terminal illness, whatever, should not be declared via post-it. "Hey, there's half a Subway sandwich in the fridge": sure. "Let's be together always?": Not so much. Not a case where you want to say it with office supplies.
5) The message on the post-it itself: "Come and go as you please but stay with me always." This is confusing. Do they want me to come and go as I please or stay with them always? WHICH ONE IS IT?
6) For example: What if I left for Bulgaria for like several years? Would that be okay? "Hey, I'm back!" "But you were gone for several years!" "Yeah, I went to Bulgaria. You said to come and go as I pleased." "But I've married and had children with another in the meantime." "But I said I'd stay with you always!" "But you left." "But you said come and go as I pleased! Jeeeez, mixed signals, much?"