​It's safe to say Stranger Things co-stars Natalia Dyer and Charlie Heaton have taken their on-screen romance off-screen. After much ​speculation, we still haven't gotten certain confirmation, but it's pretty obvious they're a couple!

And when Natalia celebrated her 23rd birthday this weekend (Jan. 13), Charlie didn't shy away from posting an adorable message for her.

Taking to Instagram, the actor posted a photo of Natalia sweetly smiling, holding a cake.

The caption reads, "Happy 21st birthday! @nattyiceofficial I hope it’s a great one and I’m stoked to be working on this new series with you. I think it’s gonna be great. 🎂🎉🥂🙏🏻 P.S - Not feeling too well but I still wanna meet you at piedmont park tonight x"

We have so many questions! First of all what is this "new series" he speaks of? The third season of Stranger Things? (Charlie is British, so they call a "season" a "series").

As far as him saying "Happy 21st birthday," fans realized this photo was taken on her 21st birthday while they were shooting ST.

Also, meeting at Piedmont Park? Sounds awfully romantic to us! We need all the details, Charlie!

Regardless of what the two did on Natalia's birthday, they are absolutely adorable together. We ship them!