The Cambridges and the Sussex's are clearly taking two divergent paths in life.
The former have chosen duty, responsibility and conformity as their path (William is going to be King after all). The latter have elected for freedom of choice and abrogation of responsibility. These divergent paths likely explain the conflict that has developed between William & Harry over the last year or two.
Not too long ago, the two brothers had each others backs, and were each others best friends. This is no longer the case. I imagine there is a lot of hurt feelings on William's part regarding Harry's choices. I think William feels abandoned.