Oh my God...! I feel like I just had an epiphany with your theory. I'm taking your interpretation (if you don't mind and not as my own of course) to further understand the story and its characters; it might as well be true! Allow me to share:
In the commedia dell'arte, Columbine chose Harlequin over Pierrot, but in this story, Columbina chose Pierrot. The role of Columbine is a soubrette which is not exactly what Columbina was portrayed -- more of an ingénue. I thought that Neko just decided to go on with his story and not follow exactly the stock character, but it does make sense: Colombina has chosen Harlequin in the end for she has turned to him for protection (despite rejecting him all this time). Thus, she probably didn't love Pierrot for what he is but mostly for the attention, gifts, and protection he was offering... And so it was easy for him to get replaced: all she cared about was to live, not him...
That is just insane because then it would make Pierrot's character more tragic (as it already was), defend Harlequin's actions (just a little since it explains why the rest were not so fond of her/why it was so easy for them to be okay with her death -- she was exploiting Pierrot and lead him to agony), and tell more about Columbina's true character.Not even a monster could love Pierrot... This is of course just a theory and personal speculations. Thank you for sharing this with us @Princess Spooky Suki! KUDOS ❤