My girlfriend is 6 days delay and experience spotting today, is it a sign of her period coming? i am pretty sure that pregnancy is not possible because we never did intercourse and she have no contact in semen nor pre cum. is she okay?

Many things cause a woman's cycle to vary in length including stress, time of year, hot and cold weather, and effect of other women living in the same house. From your question, it can be inferred that you both are intimate with each other, just not sexual intercourse. Now is a good time to discuss being responsible and using more effective birth control prevention all the time.