--you say that you already make enough money. Have you considered that this isn't actually about the money for her?
You don't NEED to work these extra hours, but you are, and in doing so, you're taking away time from her (and your family, if you have kids). And that money isn't going towards the family or towards shared financial goals, so not only is she (And the family) being set aside for unnecessary labor, she feels like she is being further shut out by you when you don't allow her a say in what happens with that money. So you're taking away time from her, AND your taking away her feeling of equality in the relationship.
As you say, yes, she could do the same as you and do a side gig or two and make some extra scratch. But I would venture a guess that she wouldn't do that, because in her mind, she would be taking away even more time from you and your relationship.
How much time do the two of you spend together, really focused on one another? Do you have regular date nights? Spend time alone together without the kids, that isn't dedicated to chores or the like?