DH and I were talking about this the other day as a friend of ours has just separated from her husband.
Over the course of their marriage, she's always earned more than her husband and also brought up the children almost entirely by herself and he was a selfish git.
He started numerous business ventures that ended up costing them money, so they remortgaged the house to clear the debts he'd raised. He cheated on her multiple times and has now moved out, renting his own place elsewhere, that's not big enough for the children to go and stay with him, though they're older and don't want to see him anyway.
He's "generously" told her that he'll continue to pay his half of the mortgage until it's paid off, then they'll sell the house and split the proceeds.
Legally, I know this is right that the house should be split 50:50, but morally it feels awful. Compared to what they'd each contributed over the years, both financially and in terms of time and effort, he will end up with far more than he should.
He'll be able to buy himself a little one bedroom place mortgage free with his half of the house, yet as she's still left with the (by then adult) children, she'll have to either tell them to move out and find their own place, or buy something of a similar size to what they're in now, to house them all (or buy him out of his half of the house).
So, just at the point that they should have been mortgage free, she'll have to take another mortgage to get shot of him.
That said, if they hadn't been married, there wouldn't have been any difference really. Neither of them have any other significant assets.
I think I'd only advise someone to not get married if there were other significant assets that the other person would potentially have a claim on later. That would apply no matter which person had the most money - husband or wife.