I can only offer my evidence anecdotally, but one couple consists of a wife who is a social worker (MSW) and a husband who is a fireman. He earns more than she does and it's been a solid marriage for a long time. Another case is a cousin of mine who graduated college and is a DJ while his wife is a personal assistant with two master's degrees and is pursuing a doctorate. She may end-up making more than he does at some point but so far she hasn't. They also get along famously and have since the day they met. No issues. Another cousin has a master's degree and she only seems to date guys with barely any high school education. She's approaching marriage number 4 and in all cases, she out-earned all her husbands. A co-worker openly complained to me that his wife made quite a lot more than he did and it was a source of friction for him. Right now they're just, "focusing on the kids," though I wouldn't be shocked if they separated. Another cousin of mine divorced when his wife's career skyrocketed in comparison to his which, as an account exec at a Madison Avenue ad agency was very respectable. In all cases I felt there was resentment and a feeling of not being, "in control," or just plain, "not needed."

Now I know a few gay couples where the difference is pretty huge and some of these range from daddy/boy to Phd/high school. What seems to matter more, and I may catch Hell for this, is who is the dominant person in the relationship (and that doesn't necessarily correlate to who is... ahem... the pitcher or the catcher). It's generally harder for gay men to have long term relationships, but it seems that when they do have them, money isn't much of an issue. Maybe it's easier for the partners to empathize and so work harder to avoid money issues, maybe there are different "marital" values at work, maybe they both know that finding a good man is rare and difficult and so work harder. I truly don't know.