How close is too close?

So i have this friend, he's my best friend actually. we've been best friends for over six months now. He knows everything there could possibly be about me and vise versa. He loves me an is in love with me. i love him as well, but my question is, how close is too close? could he actually be the one for me? could he be the one for me in the end? I dont know. Thing is, with eveyday that goes by, hanging out with him, only keeps me wondering at the end of the night. He's been there for me when i was with my ex boyfriend for 4 1/2 months (Dec-Apr). throught the break ups and the get back togethers, my best friend has been there for me. he hasn't been with anyone because he's been waiting to be with me all this time. & i am fully awear of this. Its sweet. &i've been going on with my life, talking to other guys and what not. and so has he. thing is, im soo jealous whenever i fid out that he's talking to another girl or if he tells me that he's gonna be hooking up with one. Ill usually tell him that i dont want him too, and he'll most likely wont after that. But for someone who has gone through this before, can you help? i want to know what the reason is that he's my best friend, but he's too close to me as if was meant to be more..