When you marry somebody, you are marrying:
- Their family
- Their past
- Their present
- Their future
Make sure you consider all of the ramifications of that. Do people not spend even one minute to consider this and the consequences? This is a package deal. You can't pick and choose which parts of them you want and don't want.
Does this dude not consider the fungability of money? If they're going to run separate finances and she uses her money to pay for the loans, she won't be able to afford to go on the vacation that you can easily afford. If you run finances combined, her and your money gets dumped into the same pot, and it's not like you're doing accounting to see which dollar went where. If you do, then you're back to running separate finances. See above for how that turns out.
Moral of the story, make sure you're marrying the right person. Nothing else will really save you if you're not. Things like prenups and communication can help, but don't lose sight of the bigger picture. Those are just bandaids that won't get you out of situations with really serious damage.
Conversely, why on earth did she marry someone that would be drawing lines around what he isn't taking responsibility for? Either accept her baggage, or stop dating her. You don't up the ante.