Arkansas's age of consent is 18.
A 19-year-old male dating a 16-year-old female engages in conduct that violates Arkansas law if the relationship includes sexual activity (broadly defined).
Arkansas has a limited close-in-age exemption for minors both under 18 (e.g., 16 and 17). It does not apply when one party is 18+.
While non-sexual socializing may not be prosecuted, the legal risk is extreme. Any allegation triggers mandatory investigation.
Do not assume it's legal. Wait until both parties are 18.