Hi Lina, Without the "what", this sentence would not be correct. "What she wanted" is used to draw attention to the fact that she had something in mind, which did not happen (although other things DID happen). As for the sentence without the "what", I can not make sense out of it, and I'm afraid I can't explain why. Hopefully someone else might have an answer to that...

If there's no "what", that sentence won't take for all in all :) ... And coming after preposition, there are no subject :)

The verb /to want/ is a transitive verb, therefore it needs a subject and a direct object, which can even be implicit, but in this case the direct object is given by the term /what/, which can't be implicit as the sentence without /what/ could be finished in several different ways, as in: She said everything happened except she wanted even more of everything So, as the meaning is driven by the speaker and not by the listener, it is the speaker's (or writer's) responsibility to avoid ambiguities or total lack of meaning, and the syntax rules are humble sentinels to this important fact.