What were the reasons for the weakness of the Crusader states?

After the Crusades, Christian states arose in the territories occupied by the crusaders.

The main weakness of these states was their fragmentation, in the absence of a single ruler. Often, Western knights entered into battle with each other, exhausting their own strength. The rulers of the Christian states of the Middle East entered into alliances with the Saracens for the sake of victory over their opponents – the crusaders.

Also, the reason is that these states did not receive serious assistance from Europe, scattered and small detachments arrived.