Do I need to observe niddah even when I am not married

Greetings and blessings

An unmarried woman is also forbidden to have any physical contact with a man because of niddah. This remains so even after the menstrual period has ended, since until she immerses in the mikveh, the prohibition of niddah is not removed, in addition to the prohibition of relations without marriage.

With blessings - Binyamin Shmuali