Ah, but your horcrux isn’t a water molecule to be split it’s the hydrogen atom itself so if it bonds and you split the bond the horcrux is still intact.
Like if the diary were put into a bookshelf it wasn’t destroyed by removing it from the shelf.
You can split a helium atom into two hydrogen, but good luck splitting a hydrogen atom.
Ah, but your horcrux isn’t a water molecule to be split it’s the hydrogen atom itself so if it bonds and you split the bond the horcrux is still intact.
Like if the diary were put into a bookshelf it wasn’t destroyed by removing it from the shelf.
You can split a helium atom into two hydrogen, but good luck splitting a hydrogen atom.