#1 Non-stop nagging.
When she pinpoints every tiny imperfection on the relationship and keeps nagging about it continuously, and tries to stretch it as grounds for the breakup.
#2 Tagging an individual with ‘Just a friend.’
Make sure to watch her expressions while you question her about the new person in her life. If you see unease on her face or if she’s trying not to face you that means something fishy is there.