If it bothers you and he is aware, why would he want to continue with the behavior? Respect is a key component of the love relationship. Of course there are different levels of flirting, so it could be minor, or it could be interpreted ( mistakenly) by the receiver, as being desired and/or wanted by the flirter. Is it done in front of you, as that would be quite disrespectful to you, as it would appear to outsiders that he is looking for something more than what he has with you. Define what you observe with the “over friendly” you state earlier? Was he like this with you when courting you before becoming significant with you? Can others interpret this as his interest in them?