i am 16 dating a 20 year old we are not having sex. is that illegal?

It is generally not illegal for you to date as long as there is no sexual activity involved. In Arizona, it is generally against the law for anyone eighteen years or older to have sex with a person under the age of eighteen. (A.R.S. § 13-1405). While there are exceptions (defenses) they should be read carefully as the law is provided to protect the minor. (A.R.S § 13-1407(F)). Also, A.R.S. § 13-1401 defines the terms used in these statutes. Generally, If all of the following are true, then it is not criminal for two teenagers to have sexual relations:
1. the minor (or the younger person) is at least 15 years old
2. the older person is less than 24 months older than the younger one
3. the activity is consensual
4. the older person is under 19 years of age or still in high school