To play devils advocate, if he insists on her being a stay at home wife with the kids (if that's the situation) then it's only fair that he does help pay her student loans. She failed to mention why is she unemployment, which would have made the situation more clearer.
With that being said, dudes aren't looking at the bigger picture of the situation. If she defaults on those default loans, then they're going after both of their joint tax returns and whatever property they have together even with it being her loan.