What a nice thing to be thinking about, to help future her with big expenses.
Remember that if you open an account in her name, it's her money, meaning that she can use it however she sees fit. Hookers and blow, if that's her choice. If you want to have money set aside to help her with future expenses like a wedding or a house or retirement, you might think about a separate account in your name so you have control over how the funds are used.