Is it legal for a 19 year old to have sex with a 16 year old in Oklahoma?

It is not statutory rape. See https://en.wikipedia.org/wiki/Ages_of_consent_in_the_United_States#Oklahoma

What could happen ?

Both adults? Then not statutory rape. Potentially she could be arrested as a prostitute and you could also be arrested, at least in...

Can my son 23 get in trouble if he had sex with his 16 yr.old girl at the time ?now 17 and wants to break up after dating 1yr.

If she wants to break it off, he should honor that request, even though it hurts. It is the nature of young people that they change. That said,...

Can a 19 year old girl date a 16 year old boy and is it legal or illegal to date?

It isn't statutory rape even with sex, however it is not all that wise, either. The brain of a young man does not mature until around age 25....

In the state of Indiana, is it okay for a 20 year old and a 16 year old to have a consensual relationship with sex. Parents okay

It is not statutory rape. It is not all that wise, though. https://en.wikipedia.org/wiki/Ages_of_consent_in_the_United_States#Indiana Dating is...

How can I prove my fiance is innocent on supposedly rapping a female that reported it after 2 years

His own lawyer is in the best position to deal with this. Generally mistake as to age is not a legal defense no matter how justified.

Yes. He can be charged. Whether he will or not is a separate question that we are not in a position to answer here. You need to focus on staying...

Is it illegal for a 16 year old female to talk to a 24 year old male in a non sexual way?

Dating is not regulated by law. Sexual conduct is. - Sexting with a minor (<18) = big problem - Images of minor (<18) that are sexually explicit...

Can a 16 year old going on 17 date or have sexual interactions with an 18 year olds still in school?

It is not statutory rape. The age of consent is 16. https://en.wikipedia.org/wiki/Ages_of_consent_in_the_United_States#Pennsylvania

Also, as to those texts... Look up the definition of "child pornography" and the penalties.