Advice to help a friend who is being groomed and isolated by a guy

Problem/Goal: I have this friend who is starting to distance themselves from our friendgroup because of a guy and it's starting to get concerning and we were wondering how to save her from the worst case scenario.

Context: so this guy (M22) suddenly came into our friend group and suddenly parang nag-revolve na yung mundo ng friend ko (F18) sa kanya. He has a girlfriend na and older siya sa amin pero napapansin namin na parang mas naging close na yung relationship ng friend ko sa kanya that it started bordering into intimate territory na.

They would hang out on their own and nakikita rin naman na the guy would cling to our friend to the point that he would go so far as to kiss our friend in the cheek.

We are so concerned about our friend's safety kasi halata na that the guy is isolating her from us dahil sinasabi niya na para bang wala ng tao sa kanyang side whenever we try and voice our concerns towards her. And the guy would be the one she goes to for comfort.

We are just so weirded out by the guy's behavior and it's obvious na the more nag-hahang out yung friend naman sa kanya, nagbabago rin ugali ni friend.

Marami ring nakakatakot na nangyari na I can't specify dahil ayokong madiscover ito.

Takot lang kami na may mangyari dahil sumasama siya sa malibog na friendgroup ni guy kapag nagiinoman sila without telling us kasi alam niya na pagsasabihan namin siya.

Previous attempts made: we really tried talking to her ng paulit ulit ngunit parang wala lang sa kanya dahil tinatawanan niya lang at na-ooffend siya whenever we raise the issue.

We are very concerned dahil hindi na namin alam yung gagawin. Gusto lang namin masigurado na walang masamang mangyari sa kanya.

Thank you, reddit.