I assume it's along the lines of...
"She is a pawn" (devious) > "Oh no- I'm starting to fall for her, but my goal is important!" (dilemma) > "What is she doing? She is so different now..." (interest) > "Who is that man? She used to be mine!" (jealousy/possessiveness) > "She will be mine! I will use everything I can to succeed and no one can stop me!" (obsession)
Romeo is a selfish man and only follows what he wants. He doesn't care about what other's think, so he doesn't care if the FL likes him or not; he just wants her back beside him.
Romeo is narrow-minded to the point that it doesn't even register to him that even if FL is beside him, Romeo won't ever be treated the same way as FL behaves with the ML.
It is your regular case of a person who severely lacks any empathy. Romeo cannot understand the FL and he cannot even fully understand what he truly wants since he's been having trouble managing his own emotions, but since it is subconsciously eating him up, he cannot think properly, so he eventually acts on impulse.
TLDR; Romeo is smart with his grand schemes, but he is a FUCKING DUMBASS when emotions come into the equation.
It's obvious that Romeo likes or is just possessive over fl but I really want to know what is going inside that little brain of his cuz I don't think she would be attracted to a man that left her and then even killed her grandmother infront of her