Ah - i think i might modify my first comment then if online tutoring is an option for her.
I do think it is preferable to have a parent in the home.
My DH and I (we are a generation back from you and our first was born 1993) agreed that i could drop my hours to part time after DD was born.
He would definitely have agreed to have me at home full time but no way could we have afforded that in our 20s with mortgage rates up at 15%. I also earned more then.
After child 3 was born, paid childcare was prohibitive and i gave up my career as a speech & lang therapist and switched to childminding.
That worked so well for us. I did ALL the housework, all that our kids needed and contributed £1k per month to our income. DH went to work and put the bins out🤣
Then - 2014, our youngest child started primary. I decide to return to speech T.
Did this go well? NO!!! And who could not cope - DH! It was such an eye opener to him that i actually did a lot more besides childminding.
You should have seen him stress when i left before him one morning, he then got up and DD was too ill to go to school!!!
I went back to childminding. Home harmony resumed.
Now, our youngest is 17. I do less paid work than ever. I only contribute £650 per MONTH. But i still do all cooking, cleaning and am the support person for the 'kids'
DH still goes to work and puts bins out!
I am nearly 60 now. I will get a tiny, weeny pension at 60 but, if i stop work at 60 (which i hope to) i will really be supported by DH.
But i think now he appreciates all the stuff i do at home. We have 5 kids so, to my mind, i have worked and also supported him to be able to go to work without stressing. I have loved being at home; i appreciate that he has supported me in being the main breadwinner.
We have paid off our mortgage, DH income very similar to yours.
If we were in a financial pickle, i would do more work. Of course i would.
So - i think what i am saying is have a conversation with your OH about how she feels. And, especially how she feels about the financial position.
Is she hearing your concerns? Is her interpretation of your joint position valid (presume she is not concerned?)
Does she need more support from you to help set up a business (that is what online tutoring would be)
But, never, ever under estimate what she does already. Housework is bloody hard work! Being an unpaid driver, confidante, cook, cleaner etc etc is not NO work. It is undervalued.
And - chat to your kids too. Teen mental health is in crisis just now. If your kids are happy and healthy, that is is no small part down to your DW.