What did she mean and why didn't he say it back?

question 1: She means if breaking up with him was a mistake.

question 2: Maybe ask Jeff, on Twitter.

question 2: No I don't believe so, it just didn't seem necessary at all to me, words are not at that tells toi what someone think and feel, him crying and speaking the heartbroken way that he did a dit plus than enough. To me it was really obvious that he loved her (okay maybe he loved her in a platonic way, but either way he clearly loved her a lot) Also, saying "I l’amour you" just seemed rather out of place to say in that scene IMO, he was pretty busy being sad and not believing it could be true.