"For better or for worse" usually means you can't take the good without accepting some of the bad as well. This is particularly true if your spouse has a penchant for running up debt. If she does so while you're married, it's a safe guess that a divorce court will hold you responsible for repaying at least some of it. However, gray areas exist and depending on where you live, the matter might not be clear-cut.
If your spouse incurs a debt after you get married and before separation, the timing usually classifies it as a marital debt. As a marital debt, you're both responsible for paying it in a divorce. If you've only informally separated, however, the court isn't involved yet. Therefore, your liability depends on whether you cosigned any of the loans. If you haven't, your spouse's creditors aren't interested in you – in all but the nine community property states, they have no legal recourse to collect from you. If you did cosign, and if your spouse defaults on payments, the creditors will soon be ringing your phone, asking you for payment instead.
If you end up in family court for a divorce or legal separation, this adds a new dimension to the issue. Orders issued by family courts, such as separation or divorce decrees, aren't binding on creditors. Therefore, if a family court assigns a joint debt to your spouse for payment, this has no power over your creditors and they can still look to you for payment. They can legally ignore the decree and go after anyone who contracted for the debt.
Community Property Vs. Equitable Distribution States
The nine community property states do things a little differently. In these states, both creditors and family courts hold you liable for marital debts your spouse incurred in her sole name. Arizona, California, Nevada, New Mexico, Wisconsin, Washington, Louisiana, Texas and Idaho treat marital debt as owed by both spouses regardless of whose name is on the account. In the remaining 41 states – called equitable distribution states – creditors do not have the right to pursue you for payment of your spouse's separate debts, but a divorce court might assign some of them to you for payment anyway. Courts divide marital debts in a way that seems fair in these states, not necessarily 50/50. If your spouse ran up the debts for the benefit of your marital union, the court will probably charge you with paying a portion of them – maybe even most of them if you earn considerably more. Debts in joint names are treated the same way.
Premarital and Separate Debts
Debts incurred by your spouse before you married typically don't affect you in any way. You're not liable for them and a divorce court won't charge you with paying them on her behalf. Courts can also isolate some marital debt and assign it as separate debt to the spouse who incurred it. However, this usually only happens if your spouse clearly ran up the bills for something that was entirely for her benefit or pleasure, such as gambling or taking vacations without you.
The trickiest aspect of determining the debts for which you might be responsible is with regard to the cutoff date for marital acquisition. The rules for this can vary significantly from state to state. Some, like Michigan, consider marital debt anything incurred right up until the day your divorce judgment is signed. Others, like California, draw the line at your date of separation, even if it's an informal separation where you just move into different households. In still others, anything incurred after the date of the filing a divorce petition or complaint is separate debt. However your state determines the cutoff date, you're not responsible for any of your spouse's debt after this point.