I don't understand the question.... Stephenie Meyer wanted Jacob to have a happy ending too, so she had him imprint on Renesmee. Jacob and Renesmee can both live forever. Even though... "there is never enough time to spend with you. But we can start with forever."
In the Twilight series, when Jacob imprints on Renesmee, it's meant to signify a deep connection and devotion that goes beyond romantic love. It's a supernatural bond that is meant to protect and care for the person imprinted on, in this case, Renesmee.