I don't have a problem with this. This has nothing to do with romance, at the moment. They are two lonely messed up teens. One who has a death wish and refuses to live her life because of her twisted attachment to the dead. The other, whose true motives are unknown, is also obviously twisted. Though I think it has something to do with his parents (his lowly mother, for one). It felt like he was talking about himself during the fire. It's not the first scene that made me feel that way. That "family" is all f'ed up and he claims he has thier best interests at heart ( or something like that). Maybe he wants to "clean" house and remove all the twisted bastards and restore the family honor/name/etc. He needs help to do it.
So to me, him burning down a rotting structure that could come crashing down on her at any moment (since she broke a support beam) isn't something I'm upset about. She was living in a tomb. The important things are safe, the garden and the tablet. He took great care to make sure that fire didn't spread. All the shrubs, bushes and maybe nearby trees were cut (the bushes were definitely cut, you can see it). He is calculating, manipulative, decisive, selfish, somewhat cruel and a bit unstable but he is not stupid. He does seem to like her but I don't think he sees it that way, yet. She is useful and interesting but she also unexpectedly breaks him out of a dark place. Like when "Aunty" molested him. He quickly got out of there but was in an obvious dark place until he bumped into a buck naked Ran (and her reaction) that knocked that dark moment right out of him.
Also, Ran isn't blushing in any of these dark moments and isn't suddenly cheerful. The only time she blushes or was happy is when she thinks she is going to be reunited with her Grandpa, when she talks about him or when embarrassed. None of it was romantic. This poor girl can't live because she wants to die. She needs to learn how to move on and realize her life has meaning and IS worth living. It's hard to tell if she saves people because it's the right thing to do or because she selfishly is hoping to die. Like, will she help people if death wasn't a possible outcome. Also, will she realize that her life gained meaning when she saved these people? They would be dead or severely injured if she hadn't.
Last thing, she had her freedom when he let her go the first time and the idiot CHOSE to come back with medicine. He was scary and dangerous and she still came back. She screwed herself in that moment. Her deathwish put her in this situation, if she had been capable of moving on instead of clinging to grief and death, she would be living her life away from drama. She is responsible for her current situation too.
My apologies for the mess. The above is all over the place but I wanted to talk about certain things before I forgot them.