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 an 18 year old allowed to date a 16 year old?

In New South Wales, the age of consent is fixed by law at 16 for both heterosexual and homosexual sex. It is important to understand that it is not a crime for children under 16 to have sex! The law criminalises people who have sex with under-16-year-olds.