Spenders vs. Savers
The problem: He loves to splurge, you don't. Or vice versa. The spender thinks, "If he cared about me, he'd want to see me happy." The saver thinks, "If she cared about our future, she'd spend less."

The solution: "Realize that your partner's spending style may have little or nothing to do with you," says Jonathan Rich, Ph.D., author of The Couple's Guide to Love & Money. In fact, his style is shaped more by his life over the decades than by your relationship. Rich suggests a neutral opening ("We need to talk about money") and an uncritical approach. Make it clear that you're not out to win an argument but to find a compromise, and that you know both sides must change.

Separate Accounts vs. Joint Accounts
The problem: You disagree about whether the two of you should merge all of your money, and you feel threatened by the opposite point of view.

The solution: As with many financial disagreements, there is no right or wrong side. One of you worries about money being hoarded in a secret account; the other fears having a joint account misused or even emptied. Keeping separate accounts, Rich says, can "provide both of you with some freedom. But you have to agree not to use the accounts as a way of deceiving each other." Joint accounts, he says, "may give you a stronger sense that you're working together." But you can't nitpick about small expenditures you disagree with. In either case, you and your spouse should regularly review your finances so that neither of you faces any unpleasant surprises.

Next page: 2 more problems: kids and "financial infidelity"