Not all potential spouses are up for the lifestyle... some are smart enough to know that and will remove themselves from matrimonial consideration, but some just don't know better until they find out the hard way.
It's incumbent on YOU to assess how any particular girl is going to handle it (independence is key). Just because she's fine with it as a girlfriend does not necessarily mean it will work out with 2-3 kids in the mix.
The penalty for screwing that up is paying for her and the kids to live the lifestyle while you pick up OT to make ends meet and try to see your kids around your work schedule and at her convenience. Divorce is not kind to pilots, try hard to avoid it.
If you're already married and considering a career change, the same applies, but obviously it's the wife not the career which has priority.