@NeatBiscuit
The tone of your messages describing the desired financial arrangement is cold, but hopefully you use a different tone when you speak with her.
I can understand that you fear increasing your commitment through cohabitation / having a child / marrying her, if that then gives her the right to take away half of your accumulated wealth from your past work at any time and for any reason, especially given she has broken up with you three times over the past year. In fact those breakups over this short period might be a sign that you are not compatible anyway. How long have you been together?
However, I do also understand the point of view of PP who make the point that if one of you reduces work hours and income from work, then that person will be financially very vulnerable — especially if it is her. Whereas the PP who suggested that you just sign over half of your assets to her right now is illustrating precisely why you have a legitimate fear.
It may be too late to recover this anyway, but if you do want to try - perhaps start by asking her what are her fears and feelings about this agreement? And see if you can make her feel heard?
Then perhaps on another occasion, see whether you feel that she can hear your own fears about just proceeding with the relationship with absolutely no agreement.
If you want a third party to help with these conversations, then a couples’ therapist might be more effective than a lawyer.
Then, there may be a way to draft an agreement that addresses her fears and also yours. For example - if her (well founded) fear is about being trapped and broke if one of you takes a bigger career hit to care for children - especially if that person is her - maybe that can only be addressed by pooling income — including investment income —into a single pot for some period of time, which may well need to extend beyond an eventual relationship breakdown (see below) in order to be fair.
Or maybe you would need to put a portion of your accumulated savings (but not all of it) into a pot that will remain available to support any children and their primary carer up until the youngest child reaches the age of no longer needing to be dropped off picked up, brought to appointments, etc. — so I’m talking 16 or 18, not 7 or 10.
Like it or not - if there is no asset sharing at all from the outset, then if there are children involved, any sort of income pooling would need to extend beyond an eventual relationship breakdown in order to be fair because otherwise - what if you have children, and their needs result in her stopping work, and then you break up when they are 1 and 3 and you have completely separated finances - where would that leave her, and how would it be fair to her? Whereas if you are the primary carer, you could live off of your business sale proceeds for a good while. So your agreement, as worded, leaves her in a much more vulnerable position and I can see why she would not want to sign it as is.
If she emotionally does not want ANY agreement then you may just be incompatible. But if the problem is that she will not sign THIS agreement, it may be because you have given inadequate consideration to her needs and interests.