Using a throwaway as my brother knows my main account.

Been a longtime lurker of this sub so forgive me if this post is kind of all over the place or I miss out relevant information.

First bit of background to know is that I'm fairly wealthy. Not super wealthy but enough that I don't have to work again, I started a business about a decade ago which I sold to large corporation.

My brother hasn't been so fortunate but not out of laziness, he's much better suited for manual labour which means he regularly pulls 80 hour weeks to take care of his girlfriend (now fiancee (24F) and 2 kids (3F and 1F) while saving for a house.

Another bit of background about me is that I don't believe in marriage. The courts in my country lean very heavily in favour of women during the divorce and that's why I decided long ago that I would never marry. I tried to convince my brother of the same but as I'm sure you can tell, he didn't share my views which is why he's currently engaged to be married to his girlfriend.

I've decided that as a wedding gift, I want to give my brother a house. As I mentioned, he's currently working himself to the bone working 80 hours a week to provide for his fiancee and children and hopefully by doing this, he'll ease up on his hours and spend some more time watching his kids grow up.

That's where the issue lies. I want to make sure the house remains fully his asset in case of a divorce and I've been assured by my lawyer that I can take measures to ensure this. However, my girlfriend (30F) is completely against this. She says I should either gift it to them both, or neither.

Her reasoning is that it's clear my brother doesn't share my views on marriage so I should respect that. I think that's a fair point, but this "measure" only comes into play if they divorce. If they stay married the rest of their lives together, there's no issue and they can pass it onto their children when they die. However, if they divorce, I'm sure he'll be grateful for my pessimistic views on marriage.

Another of her arguments is that if I do this for him and I'm successful in getting him to cut his hours. If they divorce, she'll be screwed over since they'll have a lot less savings than if he was working 80 hours a week. That reasoning doesn't really sit well with me. She's basically saying "He should continue working 80 hour weeks so she walks away with a bigger settlement if she divorces him".

I'm sure some people will suggest it but buying the house for him before the marriage so it remains a premarital asset isn't really an option. As my lawyer explained it, even if an asset is premarital it can be made into a marital asset through comingling of funds for example if they decide to do renovations or maintenance with marital assets.

Lastly, I want to stress that this doesn't have anything to do with his fiancee as an individual (I know she cheated on an ex, but that only factors a little into my decision). I would be doing this regardless of the woman he married even if she was an absolute saint.

TL;DR: I'd like to gift my brother a house. WIBTAH if I took measures to ensure it remains solely his property if he and his wife divorce?