Well that would depend on your interest rate, presumably. Especially since interest is tax deductible in some places.
If you _do_ break up, this also makes it harder for one person to keep the house, which might be bad if there's kids in a local school, etc. If you have 100k in equity it's easier to buy out your ex than if you have 1 million in equity.
Mathematically, yes, it depends on the interest rate. Over the reality of how humans work is people who pay their house off early are the type of people who tend to make other good financial decisions. And so paying off your house early is good advice even though it seems like it shouldn't be by any mathematical means. If you are the exception that actually has the discipline to invest in things that are better than a house Again, assuming common interest rates and other investments available - you are better off, but the reality is that type of person doesn't exist.