Why are you asking? That is, what are you trying to do?
In general, you "follow the money". If you're getting the income and paying the expenses, you can claim it all. On the other hand, since you're both owners, you can split it. What you can't do is have her claim it all.
If you are filing a joint return, you question doesn't matter. In the rental interview, you'll be asked who's income it is. Answer either way.
