Bottom line? While it's OK to worry about a partner when they're doing unhealthy things, detaching from their habits—while keeping the lines of communication open—is key. Of course, there are some non-negotiables. Illegal drug use, heavy drinking, addictive gambling, and anything severely self-destructive may warrant a "quit or else" attitude. But for those not dealing with extreme cases, ultimatums aren't the answer, and neither is an expectation that your partner will comply with your wishes. Instead, use your mutual respect to reach a compromise. For instance, when Sandra Hume complained that the smell of the tobacco drove her crazy while she was pregnant, her husband agreeably kept his chewing at a distance. "He avoids it around me in general," she says.

Truth be told, I've been lucky in that regard as well. Jon smokes only outside, away from me and the kids, and does his best to keep his habit from affecting us. Sure, once in a while he's got smelly nicotine breath, but when I ask him to wash up or brush, he amiably complies. And when I think of the major character flaws that I don't have to worry about, getting angry over his bad habit seems unforgivably petty. Too often, says Amatenstein, we think we can change our partners, "but you're supposed to be in love with the essence of who that person is."

She's right. The fact is that Jon's smoking is part of a combo package that includes both the good and the bad. So I'm going to try to take the experts' advice and detach myself from that which I can't control. I won't promise that I'll never again wrinkle my nose when I catch a whiff of smoke, and there's no guarantee that I'll stop worrying. But I'm going to work hard on expressing my concerns respectfully and directly—no passive-aggressive jabs.

After all, black lungs deserve love, too.