i don't know but if i were that girl i would appreciate it if you say/do something ._.
If the girl is not trying to get away or discourage it, then I would assume she was OK with it. Unless she is a young girl...then I might tell the guy to step off.
Mate, if you saw a walking talking flirting *******, then take a photo :)
No. She is quite capable of doing what needs to be done. It is none of your business.