She is an angel. she saw her album do well, she saw him do well. They just parted and they both found peace in knowing they found each other for help when they needed it.
She just noticed that he is truly a rock star admired by many women and remembered what she heard about rock stars not having a chance to give her what she need... Remember the conversation earlier in the movie?
Correct me if I'm wrong, I'm just checking cuz I'm not sure, did Greta cry because she realized that it was really over with her and Dave? That what they had was really beautiful and good but it was really over and add the irony of their song being played and so fitting to what happened to them? Or I'm just looking and reading into it too much? lol.
She goes to the concert in the hope that maybe they can get back together but when Dave starts to really get into playing and singing she sees that he won't walk away from it for her. When he hits those high notes he is subconsciously choosing his career over her. He doesn't realise that he is making that choice but she knows and so she cries. Love this scene :)
As above, she hopes to get back together with Dave, but finds that he chose to change their song and sees that what they had together didn't exactly mean as much to him as it did for her... which is why he left her in the first place.
he sings the song exactly as she asked him, but she realizes that he will be always in love with all the girls, with the music,with rock and that kind of life...
If you watch the movie, Greta tells Dave not to sing it like how he recorded it on the album because it lost all meaning. At the concert, he plays it acoustic at which Greta smiles because its their music and it has all the feelings of how it should be played, but then he changes the tunes and starts to play it like the record album. Like Julia and Elly mentioned, the record style shows that he's in love with the music career, his fame, how girls go crazy over it, etc. Greta realizes this that he's never gonna change and go back so she leaves