Surely ghosting would have been if she was trying to contact him and he was ignoring her? Sounds potentially like both were a bit embarrassed by what they’d done and their friendship mutually fizzled out, which I can imagine, given their ages at the time.
Obviously he was incredibly irresponsible about pregnancy, but the age of “chivalry” where the “man” (or boy, in this case) is somehow responsible for checking up that the “lady” was okay in the aftermath of such an event, is long gone.
And I bet royal courtiers have long been used to clearing up the kind of messes that spoiled and irresponsible princes have made. They were just very lucky that, in this case, they didn’t have to.