Its generally legal for a 16 year old and a 20 year old to have sex in OK.
Is it weird to date a 16 year old at 19?
There are no laws regulating dating, only sexual contact with minors. While the age of consent for the purposes of statutory rape is 16, there are other charges that can be filed against an adult who has sexual contact with a minor (under 18).
Is it weird for a 20 year old to like a 15 year old?
It is perfectly okay for a 20 yr old to find a 15 yr old attractive, intelligent, interesting and sexy. There is nothing wrong with that. This is instinctive and what everyone is trying to do is to stifle natural and normal biological behaviour.
Is it bad for a 15 year old to date a 20 year old?
Legally, nothing illegal about dating a 15-year-old when your 20. As long as there is 100% not sexual activity, and this includes hugging and kissing as it can be see as sexual contact.