Hmmmm, just my opinion but, if in the story there's this "childhood first love/childhood f...

Hmmmm, just my opinion but, if in the story there's this "childhood first love/childhood friend to crush", it's like they always WIN. Given with the amount of flashbacks, they are like the cues of being endgame.
I struggled with getting over my childhood crush too, and I CAN and MOVED ON SUCCESFULLY, BUT ofc mc in stories CANNOT. Because that would be more romantic, story wise :(( ofc not irl :(
I know ppl (including me) will support Henry with Seth, bcs it's more rational irl. But, measuring fictional story with real life just doesn't fit well.
As fiction, I think the ending is satisfying (minus the lack of closure with Seth), because from what the plots have built, Henry ending up with Sam was where they lead to. It'd have been feeling incomplete and lacking in plot if henry ended up with seth. Plus it fits very well from the aesthetic side too. Tbh, in story (just in the story), the idea of finding each other after being separated with a lot obstacles and finding true love is SO satisfying for me. Ofc, it's different irl where life is more complex.