The Ultimate problem is Israel's inability to be honest with itself and the world. The entire issue can be settled once and for all by Israel announcing it's intent to take the entirety of Judea and Smaria for itself and to permanently demise any Palestinian claim upon the region. Israel alone refuses to be honest with itself and the world about it's intent. Thus the issue continues to fester.
UN envoy to Yemen says warring parties increasingly open to peace plan (Reuters)