What else is she supposed to do? Take her husband's beating and rape? Breed him little unhappy children?
She's very technically cheating but you can't compare this to her husband's cheating. This is a matter of survival for her, he's just being nasty and trash.
I'm saying this after seeing a bunch of people essentially call for the husband's head when she catches him in the act but ignoring that she was just cheating herself. She doesn't have to cheat, she wants to. The husband is a jerk with abusive tendencies but they're BOTH cheating, and neither HAVE to do it to survive.
The husband is a misogynistic, abusive prick. Giselle is in no way near as bad as him in this relationship. But his actions don't excuse hers.
Yes, she is cheating. No she doesn't HAVE TO cheat.
Yet, to survive the emotional and physical abuse she has to endure, she needs to find something or someone to rely on to avoid losing her mind. She fell in love (lust?) with Isaac so in her mind, this is what she needed to do. There is nothing to excuse as she's done nothing wrong. She's trying to survive and enjoy her birthright: happiness. She even suggested having a divorce while her husband is happy keeping the farce going while cheating on her, beating her, raping her.
Y'all realise that she's technically cheating too right?