May-December unions: Is that his wife or his daughter?

Can 60 and 40 add up to a perfect 10? Or, for that matter, 30 and 50?

We're talking age and relationships here. As in: "Is that his wife or his daughter?" Or, "He's young enough to be my son!"

They used to call these May-December unions — and they virtually always referred to an older man with a somewhat younger woman. But with examples like Anna Nicole Smith (63 years younger than her husband) and Demi Moore (15 years older than hers), it seems clear any boundaries there once were are now about as permeable as the U.S.-Mexico border.

It's obvious the stigma is diminishing. But what I'm more interested in is: Can it really work? Does an age difference of plus or minus 10 years or more still allow for a loving, equitable and mutually satisfying relationship? Even if your beloved mistakes the Rat Pack for a Saturday morning cartoon show or thinks Ludacris refers to your wardrobe?

The best answer comes from those who have ventured into the waters themselves. As always, no real names. How else could I get them to tell me this stuff?

Older men/younger women

John, 47: I've been in and out with a woman in her late 20s that has really shocked me. I never would have guessed there could be such an interesting connection. I think the reason is, we are actually close in "emotional age." She's mature and realistic, while I am ... whatever.

Simon, 43: The biggest discrepancy was when I was in my early 40s and I dated a woman who had just turned 30. It wasn't so much the age difference that was a problem; the bigger factor was that I had made it through my 30s and she hadn't. There's just something that happens to you in your late 30s. You finally mature; you are calmer and wiser; you don't sweat the small stuff.

Scott, 51: I rarely date women my own age. I have never met a woman 10 years my senior that has ever interested me. Not that they're not out there, but the athletic, active types that attract me are less and less in that 10-years-older age range.

Terry, 50: When I was with a much younger woman (17 years), although I found her very attractive, I couldn't help but wonder about whether she found me as attractive. I wondered if someday I would look relatively old to her. The thought of me grossing her out was unsettling.

Younger men/older women

Dick, 33: Any kind of significant difference, such as education or economic status, can put stress on a relationship. I developed a crush on an older woman once, but because of the age difference, I figured she was unattainable, so I kept my distance.

Steve, 57: Having also dated younger women, here are my thoughts about older women: She has her own life, so she doesn't rely on me to complete her. This puts much less pressure on and keeps expectations to a minimum. She's outgrown her sexual hangups.

It's great knowing my partner finds me very attractive.

There's one problem in either direction: When a much younger woman selects the music, it sounds like garbage. When a much older woman does, it sounds like golden oldies.

Matt, 43: I've dated three or four women who were at least 50 and above. ... Here the biggest issue, for me, was the women's insecurities. One said it literally and the others implied it: "I shouldn't get involved with you, because it won't last; you'll leave me for someone younger." That, more than a wrinkle here or a sag there, was a turnoff.

Aaron, 29: Older women strike me as more confident, more comfortable with themselves, more self-aware, more independent — which are all very attractive traits. But I don't think it's as simple as age.

There can be 40-year-olds that act like 10-year-olds and 23-year-olds who think like they've been alive for centuries. The important thing is to figure out who you mesh with.