Maybe... they are outgrowing each other.
8, is on the cusp of being 9.
9-12 years old... is a Tween.
Developmentally, many things are going on.... cognitively/physically/emotionally.
Google search "Tween Girl Development."
For me, I would go according to MY child's cues... and common sense.
My kids, who are 5 and 9, DO stand up for themselves. And they choose friends wisely and know right/wrong, appropriate/inappropriate. And they know... when something is not right. In their... gut. I foster that in them. They have good instincts.
And they can talk to me about anything.
I don't force them, to be a friend with someone whom they do not want to be friends with.
And if they are being mistreated, whatever level that is, if my kids don't want to continue to engage with a kid, then fine.
It is okay.
Friends, do change over time and per age. And per the child's own feelings of it.
A kid can still be "cordial." But that does not mean they have to have play-dates or be, BFF's.
If my kids, did NOT want a kid to come over for those reasons, then I would not have that kid over.
After all, it is YOUR home, and YOUR kids.
And if my kids were also outgrowing a friendship or child... for whatever reason, and we talked about it... then fine.
A child, has to know... their own cues, too. And the ability to "DISCERN" that. With a parent's guidance. About life.
The other bottom-line to this is: Your own daughter, has SAID... she does not want to play with him.
So listen to that.
It does not matter how perfect or not, your own child is. She said she does not want to play with that boy.