How?

If person a is shown to have been cheating then person a loses any claim to alimony.

Pretty simple.

Person A in divorce court “judge I want alimony”

Person B in divorce court “your honor Person A was cheating here’s the proof”

Judge “ no alimony will be awarded from Person B to Person A”

Why should anyone be allowed to get alimony after cheating? That’s just insult to injury.

Your spouse cheats you walk in on it and now you want a divorce. Added bonus you have to pay money to the cheater for life???

How does that make sense?

It should literally be law that the alimony goes away at that point.