bro i feel bad but idk

hi, everyone. this is long but pls bear with me thankyouu. so i have two close friends, boy and girl. ofc im closer with my girl friend. the three of us have been friends for 3yrs and we got closer this pandemic. we hangout alot but lately our guy friend is acting weird with my girl friend. to the point she's not comfortable anymore. he's going to her house without informing her first and barging in her room without knocking (he would hide his presence and just stare at her from the door) like trying to catch her doing something idk. he would also tell us that he's 'hard as a rock' (do your guy friends tell you that his hard or are we just being sensitive??)
and she just recently told me that he would put his foot in front of her private part and he was being extra touchy (like he would rub his legs in hers) she didn't want to tell me because she thought she was just being sensitive but it just felt so wrong.
i tried talking to him abt it but he just brushed it off and we decided to cut him off.
he's still messaging us telling us to hangout and my girl friend is feeling guilty for not telling him that we don't want to anymore but i tried talking to him abt it and he just brushed me off. idk what should i do since it's a 3yrs friendship but he have so many red flags