I think the author couldn't just plain say : Yeah, they will be happy just because it's so clear. So she did her best.
The amount of 'happy' scenes this author creates as official art is the main clue to me that shippers will be very happy with the ending. The author knows that this kind of art creates tremendous expectations, even more after a story that has so much drama and suffering in between. I find it hard to believe the author is the type that baits and switch... I think she really wants to provide a hopeful expectation and that she will deliver. It's would be a bit cruel to make so many happy scenes for official art just to break the readers heart later.
The important part is 'they will be happy' ( in their own way may just be a way not to be too explicit).
genuine questions - do yall think this manhwa will end with them being together??? or it's gonna be somewhat bittersweet? cause i saw on twitter people speculating it might be a tragedy or smthn bc the author tweeted something about the ending in which "they'll be happy in their own way"
im genuinely scared cos i really want them to end up together and live happily for the rest of their lives djiskdkakd