I'm not so stupid/naive to think that doesn't exist, but it still feels extremely contradictory to me. If you love your wife/husband, you will/shall not cheat. Such disloyalty makes someone completely unreliable, thereby ending any relationship. In my opinion.
Firstly, the "stupid/naive" didn't even crossed my mind. I wasn't especially saying "it's a thing", but more trying to explain what the "thing" is and why it exist.
I understand your point of view regarding the whole situation and have nothing to say regarding it. Not only it's your right to see things like this, but in a way it's also rational. So, please, take note that my intent isn't to change your mind, but more to offer you another point of view.
This said, back on this situation.
What if I say that in fact they aren't disloyal in regard of their couple ? You'll answer that they vowed fidelity, and you'll be right, but they also vowed to stay until death...
Would you stay in a relationship that don't make you happy, or worse that make you sad ? I think that the answer is obviously "no". You'll probably try to change it at first, then pass to something else if nothing change. At least it's how it works when the relationship is still young. But what when it's a decades long relationship ? You lived more than half of your life by his side. You still love him and still are totally unable to see you aging without him by your side. It's a really strong feeling, one you can't forget that easily ; I know it, I'm a widow since 8 years and still love my wife too much to imagine starting dating again.
The problem is that somehow the attitude of your husband make you feel sad about yourself, and whatever you did, nothing changed. You can stay like this, and pass the rest of your life with this sadness ; too many do it, alas. You can quit him ; you'll perhaps (no guaranty at all) not anymore be sad because you don't feel attractive, but you'll (without doubt) be sad because you fucking still love him, which is worse. Or you can play temptress. It's innocent, you just seek for the attention you don't get from your husband, nothing sexual.
Then come the first one that make you feel really good about yourself, the one that answer really well to your temptation. It make you feel young again, it make you feel as desirable as you where when your husband kneel in front of you, asking you to marry him. The less attention you have coming from your husband, the more you fall in love with this feeling, because the more you miss it. Because it's the key point here, you don't necessarily have love feeling for the person, but you really love the feeling you have because of him. And before you know it, you're making love together...
You're now disloyal sexually speaking, but still fully committed to your couple lovely speaking. And that's why most of them have their affair at daytime. It's not by lack of excuses to stay out at night, nor by fear to be caught. No, it's because they care for the attention more than for the lover himself, and what is still more important than this attention is the desire to pass the night near the one they really and still deeply love, their husband.
Obviously, it don't apply to all "cheating" wives. Some are effectively sex addict, other don't want to loose the money of their husband. But those don't really wait before starting to fool around. The one that start having an affair on their late thirty or over, mostly do it because what I said above.
Now, I don't judge it, neither saying that it's right, nor saying that it's wrong. Like I don't expect you to change the way you feel about the situation. Like I implied above, I just offer another point of view, theirs. A point of view that also explain why I found this game badly wrote, or said otherwise, absolutely not coherent with its premise.
