The female is your best friend, and she makes friends [even get closer] to your ex-bf. although, u started to introduce both just because they were both ur friend. but they don't know each other yet.This is for my survey: How can u deal when you female friend, who make friends with your Ex-bf?
Well I wouldn't worry too much about it, like if you're still friends with him it's not a problem her being friends with him too is it?
Now if she and he get together I think she's broken her friendship agreement by not seeing a mate's ex without permission