Hi & Welcome.
Pregnancy is unlikely in case of your gf.
Usually the period can be delayed from 7 to 10 days with use of post coital pill Unwanted 72 due to hormonal imbalance. It can also change the length of monthly menstrual cycle.
Since she did not get her periods even after 50 days, the delayed period could be due to anxiety, stress, personal or professional tensions, weight gain or
rapid weight loss, ingestion of hormonal medications or medications that affect the menstrual cycle, erratic eating habits, travelling, change in climate or altitude, smoking, drinking, drugs etc.
It can also be delayed due to
hypothyroidism, PCOS (
polycystic ovarian syndrome ) &
endometrial hyperplasia.
I, therefore advise her to consult a gynecologist for a thorough evaluation for the cause of delayed menses. Get the hormonal tests such as FSH, LH, TSH, Prolactin, OGTT, DHEAS, Free testosterone, &
Lipid profile.
That will rule out most of the underlying causes.
Then the period can induced by the gynecologist by prescribing tab Regestrone 5 mg twice a day for 5 days. The periods will occur within 7-10 days of stopping the drug.
Hope the advice given above would help her.