To be honest parent-kid relationship I can't deal with them. Having said that I feel some ...

To be honest parent-kid relationship I can't deal with them. Having said that I feel some people making comments didn't fully read or pay attention when reading this manga.
The one thing that makes their relationship bearable is the fact that they were never father and son. Not in the biological way of the word but in the bond thing. They have met two times before Ryou travels back. Then he meets his not-yet-father and has problems putting them together as the same person (I would think that is because he pictured his father as one person and then he met this other person with the same name but he's not like that). So in Ryou's heart it doesn't feel like he's falling for his father mainly because he never actually had one and Konomi never acted like one in front of him. I mean come on! I've met the cashier at the supermarket more than this kid met his father!
And if you still insist on the "nevertheless he's his father" thing then I shall refer you to chapter 8 were Rypu explains that inces is only a social taboo implemented to prevent genetics diseases. It was a method used in many monarchies to keep the blood "pure" but in doing so they perpetuated "bad" genes and with them genetics diseases ran rampant. Seeing as Ryou and Konomi would not have children (the sci fi here didn't go that far) that would not be problem anymore.