You will have to tell your boyfriend that you are not comfortable with him flirting with other girls directly as he may not be aware that his actions upset you. If this does not work, you will just have to end things.
If he is going over the line, tell him in a calm voice and a time when you have some privacy and explain why it bothers you. If he continues, he can find another girlfriend who won't mind. This is usually a behavior you can't cause somebody to change and very disrespectful.
I tell u wat to do with such a boyfriend-- Just tell him that if he really wants YOU.Why is he interested in those girls?and if he is then just why not break up? then he's free to do whatever he wants to ,that jerk.I know such boys they want multiple partners and girls roaming around.So,just dump him if you think he's not good enough for you.(and I am sure he's not!) But like in some cases where the girl still loves him,You have to go slow because u wont want him to break up then?would u?Ask him why he made u his gf?and send some quality time with him and bring back some good memories.Regenerate the love felt for you at the first place and if he still doesn't consider u important then PLEASE dump him he's hopeless!!!
Basically. Life's a bitch. But if you love your boyfriend, then you need to talk to him. On the phone, in person.. text? Whatever. hes your boyfriend not all those other girls. HES YOURS. the only girl he should be paying attention too, is you and his mother. He may just be doing it to see how you really feel about him, or hes a twat, But whatever the reason. SIT DOWN AND TALK TO HIM. and if he loves you. he'll listen. if you know he wont listen then break up with him because he cant be the one.