Urinating often can also be a sign of a urine infection, it is not always an indication of pregnancy it can be for many reasons, she needs to see a doctor to rule out causes
There are many reasons for her to be going to the bathroom this often. Although many think pregnancy first hand, such things as UTI, Yeast infection, dehydration etc can cause this... she needs to take a pregnancy test with first morning urine and if it's negative, see a doctor about other causes... Good luck