Ask her. It may be she never loved her original name. Or, if she is an older boat, has out grown it. On some quiet night light a few candles for romantic affect and explain to her your reasons for the name change. Then wait patiently. You will get your answer. Always a good idea to take the time to stay on good terms.
I racked my brain trying to figure out a name.....then when listening to the song "Waltzing Matilda" by the Irish Rovers....the explanation of what Waltzing Matilda meant just "felt good.....and that it will be. Actually Waltzing Matilda is not far from the present name "Rover" (except the precious owner named her Rover because he was never able to get a dog)