uumm i think that you should go confirm (like, observe?) if he/she has the same feeling for you, but if you can't find out anything / if you are not sure, i think that you should TRY approaching him/her about your true feelings, but DON'T rush him/her because it would ruin your friendship. you should give him/her some spaces to think about it, but tell him/her that you wouldn't want this thing to ruin your friendship and you RESPECT his/her decision. some awkward periods will come but if you guys are best friends it would DEFINITELY NOT be a problem. ;) hope my advice helped! :)