literally my thoughts
For the FL .....well as I said above...she was a sheltered Princess who all her life did nothing but work to achieve her dreams of becoming the greatest pianist ever. So much that she was a nerd for it . In fact her father had created an environment where all she can do is focus on her dreams without worrying about her life . When her father got assassinated....she was still in her teens who was so shocked about everything that was happening around her her family getting killed by the orders of someone she loved ....it was too much for her too bear. She had never seen what real life struggle actually were and what really happened was that she had to face the harsh reality in such a chaos that she could not face it . She ran away from it . ML was sad for her but was also disappointed about her discussion of running away from reality but you know he was unaware that she was weak and that this was too much for her to bear and by the time he realised this ....she had already became suicidal. Now when she has grown up alot she only regrets about her past discussions. So I will say that both FL and ML are not at fault it was the situation that made them faulty
I have read the novel which was a little more detailed compare to the manhwa about their thoughts towards each other.
The ML treated FL like an angel of his life(before he met her). But when he got to know her he realised that she was ignorant towards everything that was happening in the real world ...more like a sheltered n spoiled little princess which made the ML develop hatred towards her . But the fact she was his everything made him mentally so weak that he was always fighting in his mind whether to hate her or love her or tell her about his life . Infact in novel ..he said he didn't told her anything bcoz somewhere he also wanted to treat her like a princess who has to never seen any real life struggle but still wished that she makes an approach to ask about him first which she didn't which made his hatred towards her grow more but like I said he struggled as he loved her too much as well.