I am not clearly understand what is the true feeling of waki to rikichii? Is it brotherly ...

I think he envied/ admired him. I can't say it was love.

http://www.mangago.me/read-manga/ze/an/ze-chapter-60.html/20/
Sensei did mention it in her afterword, ^^

I think Waki love Rikichi in a non-sexual way. He never want to touch or kiss him, different from his thought to Magane