Actually I totally don’t see their relationship (Nate and N’s) being romantic like I see Touya and N’s???
OKAY HEADCANON TIME BUT
I see Nate as being this over excitable kid who just wants to go on his Pokemon journey to live up to his hero Touya (and in a way he does end up living up to his name).
AND BECAUSE Nate resembles Touya so much N becomes really protective of him, but not in a lover sort of way, but more in a big brother/little brother sort of way. Nate’s just super excited that N takes an interest in him because woW ONE OF THE UNOVA HERO’S IS INTERESTED IN HIM.
N takes more of an interest in Nate when Touya returns to Unova and they meet up again; The only reason he does so being that Touya takes Nate under his wing.
So basically Touya and N not only guide Nate but keep him safe as well. I guess I kind of see them taking on Pseudo parental rolls when it comes to Nate and they just want him to stay safe and happy.