Theres not really anything illegal about the 18 year old dating a 15 year old. However, it gets to be a legal problem if dating means having sexual relations. If you are having sex with this 18 year old guy, then he is committing a felony offense that could make him a sex offender. oral sex is out, too.

Is it OK to date a 15 year old when 18?

In a Nutshell: Sex between an 18 year-old and a 15 year-old is illegal in California, meaning any touching of “private parts” of either, even with consent of both parties (and perhaps even the parents of each teenager) is illegal in California because the age of consent is 18.