She's not looking for evidence in order to break up with him, she's looking for proof that he'll treat her as a side piece. Then she'll know she really loves him.
Be interesting to see the results if the boyfriend retaliate and hires a male “10” to hit up the girlfriend.
Also interesting to see the couple. Imagine if the boyfriend is a hapless dweeb and you send a professional to throw herself at him.
More likely the boyfriend is a player and the girlfriend already knows it.
She's not looking for evidence in order to break up with him, she's looking for proof that he'll treat her as a side piece. Then she'll know she really loves him.