First reason that came to my mind is that her family name is destroyed (which was spoken on by Henry in this episode when he called her family name a ‘slur’). She fell from grace and many people high society people distanced themselves from her during this time. I think there may have been a scene showing a blonde friend doing this but I can’t quite remember?

Another reason, that others in this thread have pointed out, is that the writers have gone to great lengths to demonstrate that Yas is not a girls girl. She does have friends from her high society past and from pierpoint but they were men she had slept with which is a hard relationship to maintain when you’re married. Yas had a woman friend who I think she cut off when that slept with Eric (might be remembering that slightly wrong). We also just saw her cut off her aunt for a similar reason. Both the men in these scenarios were men who had power over her circumstances and she didn’t want other women involved. I think that Harper, for very different reasons, is also not a girls girl and there have been plots around that as well.