Im jealous with my friend and she seems flirting with him

well i have been disapointed alot with my mutual understanding to this boy
and i know were not in relationship yet but ever since we are like dating this boy and my bestfriend seems they are more close to each other
and they also text each other and it annoys me so much
sometimes i got so much annoyed when my best friend approaches us when it suppose only two of us with that boy and she would just ruin the time

and also my friend ask to that boy to help her assignment but yea she also paid him

and im kinda suspicious but i tried to ignore it

and also when my friend ask for his phone and he just let it borrow to her and while he keep letting use his phone and they are even fighting because my friend scrolling through his messenger
so i just left the room
ugh i just want them to cut off because they are too close i wish i dont find it the problem but i dont like it

and my feelings are valid if he keeps beeing this close with my friend then propably our relationship would not work out if he keeps being like this.

should i cut them off?
i am jealous its just they keep doing it and i hate it