Welll I am datin this 23 year old and I am so in love with him and I am scared, because my older sisterr threatened to press charges what can I do.. I need advise

To be able to fully answer your question, we would need to know enough of your location to know whose laws apply.

Generally, dating with absolutely no sexual contact is legal in all of the places I have looked up in the past.

You would need to look up your local laws to know where the legal boundaries are pertaining to intimate contact and sex. In my state of North Carolina it even gets into whether one person is or has been in a position of authority over the other one such babysitter, teacher, teacher's aide, religious leader, etc.

How do your parents feel about your relationship (or is your sister your legal guardian)? Besides age of consent laws, if your legal guardian(s) do not want you dating him, there could be other charges that might apply such as contributing to the delinquency of a minor or interfering with parental rights. Once again, it all depends on the laws where you reside and how they are enforced.

Also beyond sex, is your sister your guardian ? If no, does your parents know and do they care ?
Not that permssion can effect under age sex, but there are other things they can do

My boyf was 21 when I was 17

Welll I live in columbia Missouri and I need to know

Well I'm in custudy of the state right now

So does your guardian, the person over you know of the relationship and are they OK with it ?

Why not be friends for now and keep getting to know each other better first? No need to rush into a relationship so quickly anyway.

That would depend on what your court appointed guardian wants to do about this relationship. You are already in trouble, why make more, for yourself or him.

Anyone who you are in the charge of can have a restraining order put on him, with jail being the consequences of breaking that order. That's only the beginning.

It appears that in the State of Missouri the age of consent is 17, so he did not commit a crime. You can look it up here...

AGE OF CONSENT CHART FOR THE U.S.

Brittany, how long have you been dating this male? Did the relationship begin before you turned 17?

The only way I can see there being a legal issue is if you had sex with him before you turned 17 or if you did anything else with him that would be against the law at your present age such as drinking.

If he supplies you with alcohol or tobacco (if you drink or smoke), then there could be serious legal issues for him including contributing to the delinquency of a minor.

Keeping you out after curfew could also be a problem, however, it would be up to your legal guardians to enforce curfew or other 'family' related rules.

Who do you currently live with? Do you live with your sister even though you are a ward of the state? Has she been trying to get custody of you?

I think your sister is worried about you and that you need to sit down and discuss this with her. I know you seem to have your mind made up about 'loving' this man, but does your sister see something in this relationship that you aren't telling us?