
... He doesn't seem to have a moral compass - not in the slightest; HOWEVER, to me, it just seems like he lacks human empathy and can, thus, only take his own feelings and desires into account when making a decision or acting a certain way.
He obviously loves Shou in his own (sick and possessive) way but due to his lack of morals, he can completely bypass many steps when working towards the achievement of his personal goals, such as ... well, being friendly to the person he likes, developing their relationship slowly from scratch. Well, at least that's my perception of his character. Seeing how he was actually capable of breaking down mentally to that extent out of some feeling of grief or loss... I think he, in fact, DOES seem to have some milk of human kindness in him... His character is distorted, he lacks human empathy and is, hence, a very selfish and mean person but I think he's capable of 'loving' someone. He does show every sign of being a psychopath but ... I think his love for Shou-kun is what makes it hard to determine whether he's completely crazy or just completely unempathetic and flawed.
... in the end, they reunited and considering the conversation Ryuu had with his younger relative who had just realised he was gay, it appears he was going to get back together with Hitomi for reals this time.
This story is absolutely amazing; all the characters are likeable in the end; initially, I really disliked Hikaru for trying to win Hitomi over despite the fact that he could've easily phrased the provocation differently which ultimately made things more unclear between Ryuu and Hitomi who were clearly deeply in love with each other. In the end, I grew really fond of Hikaru; he's a great guy but Hitomi's heart has and always will belong to Ryuu and it appears they finally got together in the end.
The author just didn't feel the need to "fill in all the narrative gaps"; we, as the reader, can already imagine them together and they only have happiness in store for them so it's rather obvious that the mangaka didn't feel the need to draw/write more about their relationship. They've achieved happiness already; now it's time for Hikaru to find (lasting) love and happiness as well. <3
This is a masterpiece. That was all I wanted to say...(▰˘◡˘▰)