Why happens to Mikaela and Sam at the end of Transformers 2?

Thank you! Details plz, I already know Megan Fox isn't in the 3rd because she got firedWhy happens to Mikaela and Sam at the end of Transformers 2?Well Mikeala finally quits waiting for sam to say "he loves her" when she thinks he's dead she tells him that she loves him and she needs him. So at the end of the movie they are both happy because sam says it back to her they both get to hear that they love each other and say it to each other. They are happy. :( Im gonna miss mikeala she was awesome to sam.