Agree with Astrid, this happened with dd 1 last year after talking to her and giving her strategies to just join in or understand it means not now maybe tomorrow we can play etc she was fine. Maybe suggest your friend take take that approach as it's not nice that she is crying.

Dd2 is having a ball she is taking herself to her room and putting her bag outside then going back with the bell. The last two nights she has eaten all of her dinner and finished off everyone else's too. We discovered today that she has outgrown her shoes so thank goodness for late night shopping.