Well, I really don't think Ryoga's personal honor plays such a large role 
in his not telling Akane how he feels.  True, his role with Ranma is 
along the rival/friend line, but early on he still wanted to send Ranma 
"to hell", as he put it. :)  Later, he even wrote Akane a letter telling 
her how he felt, but chickened out of giving it to her.  (Of course, when 
she got it, he discovered he had forgotten to sign it, but still...)  
Where I think his honor really comes into play, though, was in the anime 
Akane and her sisters, where he tried to leave when he relized he wanted 
Akane to lose.  
Of course, Akane is still completely clueless when it comes to 
Ryoga/P-chan....  sheesh.
carlos