just understand your limits, and both of you should maintain modesty when you're around each other. dont do things which are inappropriate, keep it all clean, and ok if you want to be only friends, then we cant say anything, we're not going to tell you who to be friends with but in islam, its important to be modest and that your actions and thoughts be appropriate, thats all..
some muslims see it better to keep very far away from the opposite sex, simply because they think its wiser, for allah's (s.w.t) sake, so yeah, some would really avoid them..
as long as you're not doing anything wrong with the opposite sex, and understand your limits, stay modest inside and outside, then it should be fine.
salaam :]