I’ve now RTFT.
Some observations:
Obviously some couples share everything and some prefer to have some financial independence from each other and that is fine. I think both ways can work just fine in principle as long as the couple are both happy with the mechanics of how it works and there isn’t a huge imbalance of financial security and spending power between the couple.
To the OP:
Some of the things you’ve said about your setup do give me cause for concern.
You say that you live with your partner and children and siblings in a house which belongs to your mother. For me there are a few issues with that. Say you all carry on living in the house until your mother dies and then you and your siblings inherit it. You’ll each get a third of a house, at best. If you and your partner don’t own a property of your own, you haven’t got any equity. All you have is a potential inheritance, which is never guaranteed. Secondly, if your partner who greatly out earns you is living (for free?) in your mother’s house and you are doing the lion’s share of the childcare AND paying 50% of everything, he must be sitting on a hell of a lot of cash. Do you even know how much money he has? Do you know whether he has investments or pensions? What is he doing with all this money?
It’s all well and good him saying he wants to pay for more stuff, but the way I see it, if you are doing the bulk of the childcare for his children (AND your mother appears to be subsidising the housing costs he would otherwise have to pay) a chunk of his income should really be yours by rights.
If you were married then it wouldn’t matter so much because you would have a legal entitlement to his money and property in the event of a death or relationship breakdown.
But right now, if he doesn’t have a will with you named as the main beneficiary, you would get nothing if he died tomorrow. Your kids might get it all, but you might not be able to access it. And even if he does name you as the main beneficiary, you might be liable to pay inheritance tax which you would otherwise be exempt from.
If the relationship breaks down, you will be entitled to nothing.
I don’t want to be a harbinger or doom and gloom, but - totally irrespective of whether you have a joint bank account or not - your current set up leaves you extremely vulnerable.
However strong your relationship is, you don’t know what life might throw at you, and if I were you I would take steps now to put yourself in a more financially equal position to your partner, to ensure you are entitled to an appropriate share of his money and assets if he dies or you split up, and to make sure you have a roof over your head and some form of income when you reach retirement age.