OK, follow me on this.

  1. You want kids with a girl, but the threat of divorce rape is high, so....
  2. You decide get a pre-nup as to decrease this possibility, but.....
  3. pre-nups, while more effective than nothing can sometimes be thrown out in a court, so.....
  4. You think to just live with the person, but......
  5. You become subject to cohabitation laws where you could get destroyed anyway.....

As a result, I propose the following:

Rather than buying one large house, you purchase two small ones with distinct addresses. This way you don't get married and aren't subject to cohabitation as you stay in one, she stays in the other. When children arrive, they alternate back and forth between houses. "Sleepovers" are allowed for times of sex, but other than that, she is just a "guest" living in one of your houses. In fact, you could even charge her "rent" -aka she has to keep the place clean.

Now, obviously not as functional as having just one house, and not something I am considering in the near future. However, I theorize this to be a quality scheme from the perspective of asset preservation. Feel free to correct any errors...