Even in this age of equality, women generally still have a better grasp (not to be sexist, just stating a generality!) of what is required daily to run a household, from safety pins to bath towels and from how many apples are in the refrigerator to who took the last shower. Thus, it makes sense for whoever fits this role to put the frugal eye on the countless ways a household wastes or makes money.
Who wants to do that alone, while their partner spends what s/he has with no thought of whether they need toilet paper? To solve this problem, many couples have turned to "my money, your money and our money."
Each one keeps a portion (dollars or percentage) of his or her income and "gives" a set portion to a household account, savings, etc. The household account is used to pay bills and buy daily necessities while the rest is used for whatever is wanted or needed personally. That works for some... but if you don't talk about it and make it a priority, there are going to be some hurt feelings.
Even in the best situation, knowing exactly what is covered where is critical. You need new shoes. Does that money come out of the household account or your personal money? If from the household account, how much should be allotted? If from your personal account, should your partner have any input at all?
Many are the problems but there is one solution and that's communication. If you're not clear about what goes where, talk about it. If you feel that something is unfair, talk about it (don't fight, talk).
Like most problems, most money problems can be solved by good old fashioned common sense.
If you are able to unite your finances so there is no "your money, my money," but simply "ours," you will have to communicate even better. Set the rules if you must, although it should be common courtesy to not spend half your income on anything without consulting your partner.
When it comes to money, just like when it comes to anything else, communication and respect can make it work, whichever way you choose.
Software like Personal Capital's offering will help with the nuts and bolts of figuring things out, too. And, no, I did not get compensated for telling you that! ;)