I submitted my master's thesis draft for my supervisor to review one month before submission. He told me to revise 2 chapters because I didn't cite/paraphrase the content. I paraphrased the chapters, sent them back to him for review. He said they're fine and I continued working on other parts of the thesis. Finally, I submitted it on the final date. Between that date and the submission date, we met many times to review the draft but he never mentioned those two chapters again, so I assumed that they're fine.
Then two months after submission, they told me that my paraphrasing was too similar to the original content, and they considered it plagiarism. They then decided I failed the thesis. I can still do a second attempt, since I am not yet expelled, but I was so disappointed that my supervisor didn't recognize it during the draft review. If he let me know about this sooner, I could still revise them, so that I don't have to spend another six months on a second attempt.
Is my disappointment justified?