When I ride the New York subway, I'm the envy of most guys around me. I'm ruggedly handsome and have an understated sense of style (it seems I've perfected the sexy just-got-out-of-bed look) and I often have a big grin on my face—one that is inevitably triggered by the smart, sexy, funny woman at my side. On the face of it, we're picture-perfect. We banter; we flirt; I make her laugh like no other man can—at least, not on public transportation. It looks like a devastatingly irresistible dynamic. But not many know how devastating it can be.

You see, I'm the gay best friend. Eric McCormack, Paul Rudd, or Rupert Everett have played versions of me in movies and on TV. Or maybe you've seen someone like me on the street, arm in arm with an adoring woman, grinning at a private joke. It's the kind of friendship that has great perks. There are the late night calls after a bad date and the early morning boasting after a really good one. There's the reliable ego boosting—"Bald is the new black!"—and the hours of bad TV, usually ending in a heated debate about who's the sexiest man on Grey's Anatomy.

The connection between a gay man and a straight woman is one of the most exciting permutations of any relationship. It allows both parties to revel in the thrill of a close rapport with the opposite sex—without the pitfalls that often (OK, always) accompany dating. But though the dynamic is rewarding, it's rarely simple. Because friendships between gay men and straight women do not adhere to the strict guidelines governing physical and emotional intimacy, it's easy for them to impede the development of healthy romantic relationships.

Take Will & Grace. One of the sitcom's primary contributions to popular culture was its ability to candidly portray the feeling of being in love with one's best friend. As the title characters slipped into codependency worthy of an all-consuming romance, they found it increasingly difficult to cultivate meaningful relationships with other men. And because the list of women I've known and loved is—sadly—twice as long as the list of men I've loved and slept with, I, too, have fallen prey to what I've dubbed the "Will & Grace dilemma."

According to Jamie Bufalino, sex columnist at Time Out New York, straight women and their gay best friends may really be too close for comfort. "What it comes down to is that both gay men and straight women often have really hard experiences with men," he says. "But it's harder for straight women in these situations. Gay men might be experiencing emotional attraction, but straight women have to deal with the physical attraction as well."

Lara Smith*, 23, can attest. The Brooklyn-based teacher forged a fast friendship with Thomas Lloyd*, 32, her gay coworker, but soon found herself pushing the boundaries of their relationship. She constantly called and sent text messages, which were reciprocated and encouraged. "Pretty soon I was telling him details I wouldn't tell anyone else, going to his apartment daily, even helping him with errands," she says. The two stayed close for almost two years, often ensconced in the intimate space of Lloyd's studio apartment; both sometimes felt that the only thing missing from their relationship was sex. Intellectually, Smith understood that Lloyd was gay, but found it impossible to wish he wasn't. Eventually the lack of emotional and physical satisfaction caught up with her, and she started to feel used, disrespected, and misunderstood—and increasingly unsuccessful in the dating scene. "In the end, we had to 'break up'—at least temporarily," she says.