I never assume that I'm not 'allowed' to see other people. After turning 18, no one could tell me what I was 'allowed' to do. I'd stop seeing other people when I felt ready...when I wanted to stop seeing other people. If I still wanted to see someone else, then I guess I wasn't ready to stop seeing other people. Right? If, after the first date, I had no desire to see anyone else, then I wouldn't bother.

Without discussing with my partner what the consequenses of my actions would be, there's no way to know how the other person would react. But no one is going to allow me to do or prohibit me from doing anything. Everyone just has to be willing to deal with the consequences.