Don't mean to critisise but it is the role of the parent to set boundaries and ensure they are kept to, which will include giving your son the realisation that you can't have everything you want in life, and even those you may have, you may have to wait for. Know in advance what boundaries you set and why then you won't be confused about why you are saying, "No". Aside from that, being a parent before being a friend come with the job description, just have to accept it really. Swallow hard and carry on as if it isn't affecting you. Project the image that you are a strong adult that be relied on to know & insist on the right thing.