Lots of good stuff so far, but I'll add my $.02:

BF is high. The real estate market has all the hallmarks of a bubble in many areas, and he is playing right into it. Let me guess: he's never seen a down RE market, right? If so, then in his experence you cannot loose on RE, so why not buy the max. It doesn't work that way. RE markets can and do go down, and the leverage associated with RE can get you killed. If you have relatively little (or negative) net worth, then you can afford to speculate on your home even less than someone well-off. If I lose $50k on my home it will not be pleasant, but it won't materially affect my standard of living or ability to retire when I please. What would it mean to you? To BF? To the two of you as a young married couple with student loans out the wazoo and maybe some kids?

Keep your IRA and keep it separate after you marry. So long as things are going well in your relationship, nbody should be hurt by that. If things aren't going well, then you will really need separate assets. A la student should understand wanting contracts/legal structures in place to protect yourself without taking it personally.

Lastly, CK already pointed this, out, but it should be underscored: RE is extremely illiquid, especially when you live in it. If you think the housing market is over-valued and due for a fall, you typically can't do anything about it because it would entail moving out and paying the ~7% transaction costs. If you think that a stock is pricy, you can sel it for $12 or so. That makes all the diference in the world sometimes.