The definition of cheating always boils down to whether or not the offending person has to hide their behaviour because they know (or pretty much know) that it's crossing the boundaries that exist in their relationship.

That means different things for different people. So ask yourself what your boundaries are, and then figure out if she's crossing them.

The key determining factor for an EA though, generally seems to be when the spouse uses their EAP as their "go-to" person for anything that they should be going to you with first, whether it's a promotion, a death in the family, a struggling child, or pretty much any personal struggles or achievements.