They won't finance you because you will not be occupying the property within 90 days.
If you were married, the spouse could occupy and you could move back whenever.
Shirley's answer is wrong. They will not use your score.
They will use the lowest midscore between the two borrowers.
you have 700 - 720 - 730
and coborrower has 540 - 550 - 560
550 is the qualifying score.
The above scenario is mute since you aren't married.
If you got her score to 600 - 620 then she could buy with you as a non-occupying co-borrower.
above is an article about that program.
Have her get me a credit report. AFTER reading the book. I can try and help you after that