Why didn't Shizuka divorce Kohane after the conditions of the marraige were met?

(Apologies in advance if it's too long) Hi, i'm new to the fandom and so far ive only watched the anime so I don't know much about the manga, but I had spoilers when I went through Shizuka and Watanuki's wiki forum, I have ben a fan of the Shizuka x Watanuki ship for a while and after I watched season 2 episode 12 I was surfing the internet to see if the ShizuWata(I will call it that for now) ship still had a chance, and if the signs of Shizuka liking Watanuki had all been in my head, but after reading manga spoilers to the full story I realized they couldve had a chance if once the professinal marriage between Shizuka and Kohane had met, sice they both didn't love eachother why couldn't they have divorced and Shizuka confess his feelings to Watanuki if he had realized they were there or if there were any at all.