I honestly think he is going to go through with it. He is a lonely and desperate man, he might feel guilty but he'll certainly try to tie her to him for life and not regret it.
Also, I don't think it's going to work since she's essentially a giant void, meaning she not going to be either light or dark; just emptiness. So, I think he gonna try but ultimately fail.
I actually feel that because she's empty it's precisely why she could easily turn into a vampire. I'm unsure of course since they haven't really explained how or the process (considering it varies from story to story) but I'd still want it if Areum does as well!
And I do see your point, my wish is for him not to but he could easily be swayed by his feelings and just go through with it. I can't blame him, considering what he's been through, and he's even aware that Areum wouldn't forgive him for a good time period as well... we'll see.
I actually think she wouldn't be so against it if they were both really into each other and he HAD ASKED HER FIRST.
Sadly, I've read the next 3 chapters now and realized he actually went through with it. I'm conflicted since she's realized her and his feelings now, and they are actually really cute and getting along... I can't enjoy the fluff knowing the angst that's to come... it'll be a big blow for her knowing he's secretly transforming her...

CALM DOWN! He was thinking that, there's a good chance he won't go through with it and actually ask Areum about it! He's been showing so much development it'd be a true shame for him to go back to his forceful ways (although he's still forceful but in a different way from before). I truly hope the author doesn't follow through, Areum is getting there but not to the point of her turning into a vampire for him.
Although I'll be honest, that's the kind of ending I wish for, so that they aren't killed. BUT I WANT MUTUAL AGREEMENT!