There’s no preposition to go with the verb crave: you don’t crave for something; you just crave it.
I changed the period after about me to a semicolon because those two sentences are very closely linked. (I would also change needed to wanted, because it fits better with the meaning of the first sentence, but I’m going to leave that part alone in the corrections here.)
“I was just an object you craved. It wasn’t about me; it was about what you needed from me.”