Look up the term

BPD.

How much does it describe her?  A little?  Some?  A lot?

She is not an adult, so it does NOT apply to her.  Having this knowledge should not alarm you, but you may feel less panicky.

Talk to her like a friend.  Show that you want to know and understand her feelings.  Act like a sounding board, no judgment.  Her act may be a cry for attention from you, but not the type of negative ones you have shown.

Ask her about him.  Only when she can talk about him freely to you, you can have influence over this matter.

Hope she will grow out of it.

 

Disclaimer: not a professional advice.