A very important compilation.
In season 3 Mrs Hudson says that she was no longer friends with a woman who left her wedding early and that they lost touch after the wedding. Well, Sherlock left John's wedding early and in season 4 they hardly talk, end up fighting and even in the end Sherlock is a bit awkward with John and dosent even know if its okay to sit next to him
So in a way Mrs Hudson was right. Season 3 was the end of an era and sherlock and John were not friends in the same way they were before.