As stated before, he once thought that she might work with the korean governant. The 'saintess' used some lies to get him to cross dimensions, as he is strong.

They kinda tried to make them their working dog, going as far as to consider a forced imprint. This was decided against, as ou Fl came into the picture. 
From that point forward many threats were made against her, wich only he knew of. He was constantly trying to balance his obsession as a guide-esper, his love and his anxiety.

One way of this was to micromanage her, but also ignoring her heavily, as he thought, that if he showed his love openly, the threads would get stronger. That is also one reason, why he did some unreasonable work in korea, wich left him sometimes on the verge of breaking and the last straw was what we saw in the first chapter. (Him going on a rampage)

He got a second chance when he awoke in his own world. 

The thing is: The saontess was never the real one but what happened to the real one in the first round isnt known for me. 

So the miscommunication stems from:
1. he was suspicious
2. after he trusted her, he was afraid, that if he loved her openly, the governant would do sth to her.

While she never knew this. It is understandable to not want him anymore, although she still loves him a bit. But she just wants a normal life with her family.

The novel is nice. And the kiss between them is much more steamy there. All in all the manwha feels a little much... uhm .. pg13 in this regard.

He'll later try to destroy her, so he can at least have her husk. Until he learns that it isn't what he really wanted. 

The novel kinda climaxes into self destruction from every side. 
It was so heavy and sad, that I couldn't read the last 10or so chapters. 

BUT I can give a heads up for the side story which is set after the ending.
They kimda find togetjer again, live together ans she slowly learns to trust him.
Sadly he still has the tendency to want to lock her up. (Literally. That is just his urge, even if he stopped acting on it)