I am asking this on behalf of a female friend of mine. I apologize for my bluntness, I just dont know any better way to phrase my questions.
1) Do the halachos of niddah (sexual relations) apply before marriage?
2) Does the prohibition refer to sexual relations, or to any physical contact?
3) Is it forbidden during the period to have any physical contact with a guy, both before and after the wedding?
Don’t worry about the bluntness. The most important thing is making the question well understood.
1) The halachos of a niddah apply to married and non-married girls equally. The vast majority of unmarried girls do not go to the mikva, and are generally unaware of the laws pertaining to the mikva and the proper preparation for it, and some communities do not permit unmarried girls to visit the mikva (because of fear of pre-marital sexual relations).
2) According to many authorities (who follow the ruling of the Rambam), the Torah prohibition of niddah includes any form of intimate physical contact, such as hugging, kissing, and so on. According to other authorities (following the Ramban), the prohibition on other forms of physical closeness is rabbinic.
3) After marriage there are various added stringencies on contact, which apply only between husband and wife. Before marriage, any form of physical intimacy, including any intimate touch (stroking, hugging, and so on), is prohibited.