Regarding Sage's last name: speaking as someone who spent 8 years in college (4 years more due to the pandemic), I never knew the last name of 90% of my classmates. I had no idea whether or not there were teachers who were married and taught in the same course; or even if they were married to other employees who worked at the same college. I can count on the fingers of one hand the number of college colleagues whose last name I knew, and even then only when I had to hand in a written assignment. After that, I completely forgot their last name. Do you know why? It never made the slightest difference to my education to know that. With the exception of a few teachers (my course had at least 25 teachers), I never knew their last names or their personal lives. So, from my experience, it's not at all impossible for MC to spend so much time without connecting A with B, especially when one of the parties uses a different last name. Unlikely, perhaps; impossible, no.
P.S: I want more of Tiffani, Tara and Bianca!!!!