Most of the time when you take a friendship to the next level and things don't work out, it will ruin what you had before. There is always the possibility that taking the relationship to the next level will be good and you to will be even better GF/BF as you based it off a friendship first. I would guess that he has similar feelings but won't act on them as he worries of ruining the friendship as well. If you look at most marriages that are successful, they will tell you that they are the best of friends as well.
I Think I Like My Best Friend As More Than A Friend But Loas Of Other Girls Like Him Too, But None Of Those Girls Know Him As Well As I Do But I Don't Want To Ruin Our Friendship. What Should I Do?
You can't just set back and wait for some one to take him. You have to tell him before he is with another or it's going to be allot worse for both of you.