Whenever Kawaki activates his Karma, it inevitably triggers Boruto's Karma to activate. Why is this?
Since Boruto doesn't yet have the ability to activate Karma at will so, he can't control its activation or deactivation. The only way for Boruto to activate Karma is with resonance, for now that is and he needs to be close to Kawaki as well.
The resonance is not only limited to Kawaki's karma,
we can see that when Jigen comes to the leaf to take Kawaki back, but this time Boruto's karma resonates with Jigen's from further away.