I have learned not every person needs or wants lots of friends or a best friend.
It astounded me, because I am the opposite. I have many very best friends..
I have a group of friends that I still see once a month and we graduated from High school together.. Heck my husband and I have been best friends since we were 13!
But our daughter has never had what I would call a "Best friend".
She has friends for different occasions.. She has her "childhood friends", she has her "Art friends", "Her rowing friends", she has "family friends" , "High school friends" and now she has her "college friends".
Rarely do they mix or come together.. She is happy. People like her. She can call up any of them at any time and they want to get together with her (not that she is good about doing this). And this works for her.
I learned a long time ago not to try to press her to be someone she is not.
It just made her shut down and I did not want her to have the impression there was something wrong with the way she was.. Instead, I told her if she wanted to have her friends over, they were always welcome. If she wanted friends to join us when we went places or did things, they were welcome to join in..
I also was very good friends with many of her friends moms and we would suggest group gatherings.. This way we moms (pushy) could get together and our kids did not feel like it was so orchestrated..
There were game nights, movie watching gatherings.. We provided the space and the food. When it was time for prom, none of them wanted to go as dates, so they were just going to go as a group.. We offered a giant dinner party and provided the dinner. We invited parents over to assist with serving also take photos and have dessert with us.. Once the kids left we enjoyed wine and ate the leftovers.. It was lots of fun and it had been a huge group. The kids said they felt so relaxed. We did not sit with them or get in the middle of their stuff, but we just kind of in another room while they did their thing.
It still continues when they all gather from college.
Just talk about friendships in an abstract way. Ask who likes the things she does. See if she wants to include anyone and if not.. no big deal if she seems happy.