now, i think i get it, it is not an open ending, it is quite clear that Yuu understands Emi's feelings better than Emi itself, Emi all this time has liked Yuu, but she is not able to understand her own feelings.
the stuffed animal was a love talisman, yuu went ahead and gave it to her, as if saying, I'm not going to wait any longer, and she made the move, the "payback thing" was just a joke, like "You wanted it and i took it ", but it's clear that she wanted it for her.