Sides is the problem.
In every conflict like this each side thinks they are right to the point that their own actions are always justified because the other side is a terrorist or whatever.
Israel are a modern democracy and as such should be the adult in the room but they seem to only want peace on their terms. As the player with far less power Hamas or whoever won't come to the table to negotiate in good faith, and perhaps drop their more extreme views on the existence of Israel, unless Israel take the lead in the process but that doesn't seem likely to happen.
Again the parallel in Northern Ireland is strong. In the end the powerful nation, that the other side considers an occupying force, has to talk to and make peace with people they consider terrorists, who in turn need to talk to and negotiate with the occupiers. Until that happens the cycle of violence will be a perpetual motion machine.