Hmm, I used to have this same problem? I have liked this guy
more than a year before I could bring myself to confess to him.
Before that, it was pure nightmare. I kept second guessing his
motives everytime he did something as innocent as to message me
suddenly and asking me out, and everytime he did something for me,
I would ask myself,"Does this mean he loves me?"
So I see my confession to him as a closure. I told myself that if
the response is positive, then we will move on to become a couple.
If not, then at least I know the answer and I will never ask myself
the "what if" question again.
He told me that he only sees me as a friend, a very close one. Even
though we can spend hours just talking to each other, but he says
he feels comfortable with me, but he has no feelings towards me. So
we agree to remain friends, and until this day, the friendship is
still intact 
So, I think it would be good for you to confess to him how you
feel. Because you will not have any regret even if it ended in
rejection. And if you worry about risking the friendship, I believe
that a strong friendship can withstand this kinda test.
What happened to me after the rejection? Yes, I was hurt but after
a while, I can see that maybe Life has something else in store for
me, and I moved on. If not because of the rejection, I would not
have met my ai ai today 
Good luck 