I have a 17 year old girlfriend living in maryland where the age of consent is 16, and she is visiting me in arizona. I am a California citizen residing in arizona, both states have a consent age of 18. I am 18. If anything were to happen during our visit, is the age close enough, does the fact that she's a citizen in a state where she can give consent matter at all, or is it just illegal either way?

The law applies in what ever jurisdiction the act takes place. It will not matter where your state of residence is. When in Arizona, the laws of Arizona apply. When in California, the laws of California apply. When in Maryland, the laws of Maryland apply.

If a minor is outside their state of residency, it must be with the consent of their legal guardian or parent and they must follow the laws in the state jurisdiction they enter.

If a minor child is encouraged, coerced, transported, enticed, or aided in being transported across state lines without a parents consent for the purpose of sexual activities with an adult, the adult may be in violation of federal law.