What do you do if....?

what do you do if you introduce your girl best friend to your guy best friend. And your girl best friend ends up liking your guy friend. But the catch is you are extremely over protective of your guy friend.and your friend that likes him isn’t the type of person that stays with the same person for a long time. And you don’t want your guy friend to get hurt, and you really hate sharing him with other people. Sorry if I confused you.