Interesting thread, gerardc. I seem to share much of your philosophy and could see myself ending up in a similar situation. I think one of the central issues here is the desire to have a relationship where neither partner is dependent on the other. I feel the same way. Dependence is a big turn off for me, and I don't think I could respect someone who expects me to "take care" of them (outside of certain circumstances, such as illness, of course). Let me put it this way: my pet is dependent on me. I want an equal partner, not another pet.
Naturally, in this situation I would absolutely not be ok with my partner quitting her job and becoming dependent on me. I would expect her to continue working, pay her share of the expenses, and do her share of the chores. Which ideally would be 50%.
Now there are various things to consider. For instance, if you want to split expenses 50-50, you have to have compatible lifestyles. In other words, you can't expect your partner to pay for stuff she doesn't have a say in or cannot afford. This includes vacations. I would definitely work out a clear, agreed upon budget where both parties have equal say, which includes discretionary spending. Otherwise, what you have is two separate people living two separate lives, which doesn't seem like much of a relationship.
Since you have more money than her, you could theoretically spend more of your own money to do stuff that is not included in the agreed upon joint budget. However, I see a huge danger in doing this as I do think it would destabilize the relationship and lead to resentment and/or entitlement as others in this thread have already pointed out. If you start exercising your privilege like this, she's probably going to either resent you for lording it over her and refusing to share, or become entitled to you sharing it with her. Therefore, I believe that all spending needs to be accounted for in the joint budget.
If you are not ok with living within the confines of an agreed upon joint budget where expenses are split 50-50, then you should probably reconsider your philosophy and/or relationship. Furthermore, if the two of you cannot agree on how to allocate a budget, it sounds like you aren't that compatible and probably shouldn't be sharing a life together. I think this is a fair system. Under this system, your money remains your money and her money remains her money, but when it comes time to spend money, you both spend it together.
I do see some downsides to the 50-50 joint budget approach, like what do you do with "extra" money that you can't spend because it is not included in the budget? Give it to your partner? Donate it to charity? Just hoard it until you die? This seems irrational and could also become a source of resentment and/or discontentment from both you and your partner's perspective.
Perhaps one compromise would be to abandon the 50-50 joint budget rule and instead construct a budget based on what both parties are able to contribute. So if your FIRE budget is $60K/year but based on your partner's income she can only reasonably spend $30K/year, then you'll end up with a joint budget of $90K/year where you pay for 2/3 of everything. Note that the key term here is joint budget: your partner would be entitled to have joint authority over how the 2/3 that you contribute is being spent. This is how you would avoid resentment and maintain fairness.
It seems like a good compromise. Your partner will remain self-sufficient and pay her fair share of the expenses. You will be protected from being taken advantage of because the only part of your money that gets spent is the money which you have already allocated to be spent as part of your FIRE budget, and if things go south, there's no way she can lay a claim to a single penny of your nest egg. Unless you decide to have those kids--but hey, there's no way getting around child support. That's a calculated risk you'll have to take.
As far as kids are concerned, if you expect your partner to stay independent then I feel it is your duty to either become a stay at home dad or agree with her to hire a nanny or something, which you pay for 100%. I say 100% because in this situation you have the opportunity to raise the children without the help of a nanny, but could choose not to. I think you would have to own that decision.
Finally, I really do think it's important that you have compatible lifestyles. If you have the desire to travel all the time but your partner can't because of her job, that's probably not going to work out in the long term. Also, I don't think it's fair for her to be working hard while you're just leisuring around--again, this is a source of resentment. Ideally you would find something to work hard on during FIRE so that you still have a "job." If both of you are working and contributing to the joint expenses, what does it matter if only one of you is getting paid? Seems fair to me. All that being said, this would be a great opportunity for you to encourage your partner to pursue part time or remote work, since you have so much flexibility in your own lifestyle. Why not find a way for her to have more flexibility without sacrificing her career and becoming dependent on you?