Everybody is confused with the question if a girl and a boy can be best friends ? You can never find a perfect answer for it as the question is itself difficult. But firstly for this you need to differentiate between the definition of friends and best friends. A friend is someone with whom you share a mutual bond. A best friend is someone whom you can count on, share every bit of your heart, feel a mutual bond of affection inclusive of family relation. They are the first ones on your contact list, social media and in your heart.
Now, the answer to this question might be quiet easy. A boy and a girl can be just friends, but not best friends. If you give that bond the so called tag of best friends, you are sailing in the wrong direction. At one point of time, they will fall for each other.May be for a short time or forever depending upon their compatibility and understanding. If your friend fits well in the frame of ideal boyfriend/girlfriend, may be he/she is the perfect match. It is not necesaary that you realise it later/sooner or temporarily/forever but realisation is compulsory.
Secondly, a boy and a girl can be best friends depending upon their emotions. If a girl truly loves an another guy, might be its possible she has a best friend too. They can be best friends, because feelings do not strike or disturb their friendship. There is no scope of rebound or falling in love. Once you are in love with your partner, friendship cannot jeopardize your relationship. The silver lining between friendship and relationship can be maintained, varying from person to person. If you misunderstand the love of being friends as platonic idea of love, you are sailing in the wrong boat.
Friendship is something more than relationship. If you are best friends with opposite sex, you know deep in your heart what you actually feel for them contrary to what other friends say about you. Its something more than lovey-dovey kind of love, more mature and beautiful. Yes, they can be best friends, without falling for each other. A relationship may end up breaking after years, but friendship has no such breakdowns. Making the world crazy together, loving each other's company, laughing out loud, available when in need proves they can be best friends.