ik it's an au, it just seems kinda pointless to write it, especially since one of her main traits was that she was indecisive and throughout the story, kept jumping from guy to guy, us essentially seeing her date them all anyway.
so with the clearance on who's the final couple and and the mc deciding on who she loves should've wraped up her character arc, represented her growth. this au is contradicting all of that.
idk it just seems funny to write this?? the author shoulda just made her poly..
also "veryyy common" is surely an exaggeration.
I think you're reading a little too far into it tbh It's just a for funsies look at the other couplings for people who were rooting for the other guys. It's more so for the audience rather than having any actual bearing on the story or the MC's canonical growth. You're free to not like it, but personally I'm excited for Taeseok's "what if" because I was a really big fan of his

I don't think even the author knows who they want as the final couple