My birthday is may 31 st and I'm 15 right now. My boyfriend is November 23 and just turned 18. My parents are okay in it and his are not. Is this illegal? And I live in Washington

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

Is what legal? For you to date? If he's 18, it doesn't matter what his parent's think. There are no laws governing dating, but the age of consent for sexual activity is 18 in WA.

If your parents don't object to dating (though I would if I were them) then no laws are being broken as long as you don't get intimate.

However, I question what an 18 yr old would see in a 15 yr old. You are at very different stages of your lives now.

Why does his parents have a problem?
Do you plan on his parents causing your trouble?
But there are no "dating" laws, there are sex laws.
You can not have sex.