Continuity error?

Hi Folks! I recently watched AJLT and they seem to have missed the justification for Aidan and Carrie not knowing about each other for 18 years / not meeting / speaking?

Aidan was Steve's business partner and good friends at one point. When they break up the second time around, Carrie reaches out to Steve to figure out how he is. Seems unlikely that Aidan was never invited to any of Steve's birthdays or anniversaries all these years or it coming up in conversation otherwise?

I ask because CY expresses surprise when CB drops Aidan's name at Naya's Dinner. Miranda too seemed to have known nothing about him?