Age difference

Should a 15 y/o and a 21 y/o be 'dating' Bc my friend told me she met a 21 y/o when she was at BK and he was sweet and nice to her and she told me they talk and he wanna date her but he quit his job at the pharmacy and he quit going to college Bc he doesn't like the way they teach. She also told me he's getting his car at the end of the month so he wanna take her out. He also said he mentioned something getting her high. She's really down for him which is surprising Bc they just met and she should know this is illegal and she could get him I sm legal trouble ans he could hurt her and I'm worried