<span>There were several reasons for the fall of the Roman Empire. Each one intertweaved with the other. Many even blame the initiation of Christianity for the decline. Christianity made many Roman citizens into pacifists, making it more difficult to defend against the barbarian attackers.</span>
You could talk about the times you had together( like funny, sad, and happy times). Or the times that's she's been there for you and how this time you be there for her with every step of the way. You could also tell her how proud you are of her and that you look up to her. Hopefully these are some ideas that you could use for your speech. :)