Can Guest Service Agent (Guest Relation Officer) be a friend of Food and Beverage Manager?

Friendship is something very wonderful in the workplace. Provided that it does not affect the follow-up work and writing reports and not to be any kind of pleasantries

Yes, they can be friends. Both of them work towards customer satisfaction.If they are friends they can share ideas about the likes and dislikes of a customer. Doing so can help both of them build customer satisfaction.