I have a 7 year old son who is obsessed with one friend, it is affecting all areas of his life, what he eats, wears, plays with and so on. He follows him all day at school, copies the other child at all times, practically has to be on top of him (not just beside him) or he has a tantrum. Both our family and school have tried various techniques to get him to interact with other children but to no avail, he just finds new ways to get close to him.
One thing we discover in parenting is that we can’t choose our children’s friends, nor can we easily influence the intensity, the closeness, or sometimes the separation and rupture that can occur within that relationship.
How does the other boy and his parents experience the relationship? Does he complain? Have you talked to the mum of the other boy to see what impact it may be having on him? In other words, does the “obsession” cause a problem for them?
I wonder too, how much your son is aware of any negative feedback that his friend gives him? If your son knows his friend doesn’t like the nature of the friendship but continues, then it may be that he is acting out some other need, or experiencing some underlying issues, that may actually require some professional advice and input. It sounds like you and your family may need more help to fully understand what is going on for your son, and how best to help him.