The issue in Tennessee is whether she consented to go with him
Not sure you can charge kidnappimg federally either in presence of consent by a certain age
13 in Tennessee
For leaving with someone
Sexual consent by contrast is 18 now in 2916
Pretty sure it applies to her without regard to her willingness, IF she crossed state lines:
https://www.law.cornell.edu/uscode/text/18/1201
U.S. Code Title 18 Part I Chapter 55 § 1201
18 U.S. Code § 1201 - Kidnapping
...
(g) Special Rule for Certain Offenses Involving Children.
(1)To whom applicable.If
(A) the victim of an offense under this section has not attained the age of eighteen years; and
(B) the offender
(i) has attained such age; and
(ii) is not
(I) a parent;
(II) a grandparent;
(III) a brother;
(IV) a sister;
(V) an aunt;
(VI) an uncle; or
(VII) an individual having legal custody of the victim;