That's what happens when people want only one thing from a story. Shirayuki's story doesn't rely on her romance with Zen. It's a deconstruction of the princess/prince trope. A romance with any man that's in her life the most denies the core concept of the story that she does not need her prince...
Been following this manga for over ten years and I still get so excited when it updates. Everyone can have their ships all they want, but I love that the story is first and foremost about Shirayuki's life and her priorities as a pharmacist. You don't get stories like this often.