Looking back, which guy friend has truly been there for me... as a friend?

I remember clearly I was crying over some guy and confided in another. And he told me,
"You're a good girl. If I weren't attached I would have protected you"
"All you guys say the same thing, that I'm a good girl then try to have my body"
And then I burst into tears.

And then there was this very learned man. He would say stuff like "Meet me at the hotel and I'll help you with your socio homework"
I managed to get help for my socio homework without getting into a fling tho.

I have this guy friend that I had a brief romance with, and right now we still go to each other for advice. Recently he's had a relationship issue and came to me for help. I don't know about him but I actually feel more comfortable now, as compared to pre-fling.

Some people I met are still friends with me now that the feelings are gone.

So how? How do you establish a normal friendship with a straight person of the opposite gender without going into anything first?