I’m a 21-year-old student who’s been dating a 45-year-old man for three and a half years. He’s been technically married throughout our relationship (two years ago, I discovered he lied about being divorced). I’ve given him an ultimatum: He has to be divorced by July, when I graduate. He agrees, but supports his 26-year-old daughter and unmarried 46-year-old sister (even paying to remodel her bathroom), and pays his wife’s mortgage and bills. He manages to take me to dinner and helps with my rent, but he’s pulled in so many directions. I’m told I’m very mature for my age, but I don’t know how to handle this. I do love him very much, and we plan to get married and have children. Please don’t focus on the age difference. A 27-year-old could have the same issues with a guy.

—  Got Competition

At 21, being “very mature” for your age makes you less likely to end up on the Internet, naked and compromised, so corporate recruiters can lean across the table on job fair day and whisper, “So, tell me … were you in business school on a gymnastics scholarship?”

A few years back, you probably just missed taking a married, middle-aged dad to prom. Even if you were “mature” for your age, at 17 your greatest accomplishment is something like getting a handle on your pimples. Ask yourself what man in his 40s finds a 17-year-old girl his peer, his partner, his equal? Probably one who knows better than to hit on all-grown-up women who’d be quick to notice he doesn’t just have baggage, but a caravan of broken-down U-Hauls. Think about it: You’re planning to marry and have children (plural!) with a guy who’s not only still married to somebody else, but supporting three other adults. And you’re seriously expecting this to change? OK, it could — should an asteroid flatten all of them (ideally, Wizard-of-Oz-style, so you can scavenge any fabulous shoes he bought them).

Here you are in your early 20s, the peak of your hotitude, the time to date around and see what’s out there, and you’ve taken yourself off the market for this guy? You actually have no business doing anything of a permanent nature in your early 20s. These years should be renamed the Idiot Years (a follow-up to the teen years, the Wildly Moronic Years). Recent research by child and adolescent psychiatrist Jay N. Giedd suggests the prefrontal cortex, the judgment department of the brain, is still developing through the early to mid-20s. While individuals do vary, you most likely got together with this guy before you were fully brained, and certainly before you had the life experience to know who to let into your world and who to send back to his wife.

Be honest: You know this guy is a bad bargain — a married liar and one-man welfare state who’s bailing out everybody but General Motors. But because you got attached (perhaps both to the guy and to the guy paying your rent), you’re working very hard to tell yourself love is all you need. Be sure to tell that to your kid when he has a toothache and you can’t afford the dentist, or when you’re consoling him after he wets the refrigerator box (he’ll have a bed to wet just as soon as Daddy finishes paying off his sister’s new kitchen).

“The Big C” (ya later)
Several months ago, I started dating this woman. She’s great — just not for me. Several weeks in, I was about to tell her when she burst into tears and told me she’d been diagnosed with gastric cancer. She was diagnosed early (doctors think she’ll be cancer-free by summer). I love her as a friend, so I plan on being totally there for her, and leaving once she’s cancer-free. Meanwhile, I wouldn’t cheat, but I find myself flirting with other women.

— Am I Horrible?

When there are guys who are only with women for sex, their money or their big pontoons, only being with a woman for her cancer certainly is a cut above. But think this through. She’ll get more and more attached as you care for her in her time of need, and then, when she’s finally in remission, you’ll break the bad news: “I wasn’t really your boyfriend; I was your tumor’s boyfriend.” The right time to break up with somebody is as soon as you realize it’s over. OK, so you don’t respond to sobbing and “I have cancer” with “There’s something I need to get off my chest, too.” You have to tell her, but before you make any promises, figure out whether you’re truly up for “being totally there for her” — or whether that’s guilt talking, trying to drown out a little voice in your head that keeps wondering whether she’ll have any hot chemo nurses.

Got a problem? Write Amy Alkon, 171 Pier Ave., #280, Santa Monica, CA 90405, or e-mail AdviceAmy@aol.com (www.advicegoddess.com)