In the 616 universe, Peter went to class with Harry and Gwen, MJ met Harry and Gwen through Peter. There is also a possibility that Peter didn't went to the same college with Harry and Gwen. That is probably how Harry met Gwen by going to same classes.
I am not familiar to Gwen, except Spider-Gwen, but the preview feels a bit of Liz Allan to me or any other generic blondes.