I sent my federal return to my fiancee netspend account. They are rejecting it because my name isn't on the account what do I do

The refund will go back to the IRS.   Then the IRS will issue a paper check and mail it to the address you used on your tax return.   This will delay your refund for several weeks.   

Going forward---do not try to use someone else's bank account.   There are too many ways for it to go wrong--including what you are now experiencing.

https://ttlc.intuit.com/questions/1901159-can-i-deposit-my-tax-refund-into-someone-else-s-account