I think I’m dating someone. Yes, wait, I know I am… at least, I’m pretty sure. But I don’t know what that means exactly. Here’s where the confusion comes into play. I’ve “dated” guys and then I’ve really dated guys. I’ve hung out, hooked up, had breakfast, talked on the phone, texted, IM’d, met for drinks, had dinner even-but these weren’t guys I’d consider boyfriends. I knew that the nights they weren’t with me, they were probably with someone else, or would be if the opportunity presented itself. And frankly, maybe I would, too. Although they weren’t necessarily courting me in an old-fashioned sense, they weren’t doing anything outright wrong either.

Why would I be in a pseudo relationship like that? Because I, too, wasn’t sure if I wanted to commit yet, or-maybe more likely-I didn’t want to be the one to instigate “the exclusive talk.” You know how guys are: You bring up anything other than sports or music (or whatever they’re into), and they start fidgeting like an antsy two-year-old. Press them even more, and you can kiss any chance of a relationship goodbye (nagging!). You might as well change your name to Psycho Suzy because that’s what their friends will be calling you behind your back.

“You never have that talk until you’ve gone on at least three dates,” Mr. Popular says. “And a real date means a meal and serious, sober conversation as well as at least one ‘day outing,’ which can involve drinking and meeting up with your friends at some point.” You don’t even need to be having sex yet, he says, to just have the conversation, but it depends on the situation.

The terms of dating are so ambiguous these days that you can be sleeping with someone for months and never really know where you stand. And it only becomes more vague as we get older because we become more independent and set in our ways, making it even harder to form a union-or “become a twosome,” as my dad would say-and harder to train ourselves to think in terms of “us” instead of just me. That’s why my generation has become increasingly non-committal and is staying single so much longer. (And by the way, there are women out there who are every bit the commitment phobe that men are-I’m a recovering CP myself.)

“In my younger 20s, I began seeing/sleeping with a girl. We were about two months into the relationship when somehow the subject of exclusivity was brought up-by her,” says Matt, now 37 and married. “I told her the truth: ‘It’s not like I’m dating or looking to, but if I did meet someone I wanted to go out with, I would,’ I said. Well, you can probably guess what her reaction was-if we were going to be intimate, we had to be exclusive. I understood. So now I think, once intimacy occurs, it shouldn’t be occurring elsewhere.”

Lena, 30 and newly married, feels a bit differently. “I do not think, regrettably, that nowadays sleeping with someone means you are exclusive.

But I do think we are way too quick to take our pants off,” she says, bluntly. “My experience has shown me that if a relationship is ‘right,’ there isn’t really a need for the talk. It happens naturally and without the other person wondering how the other feels. In other words, if you feel like you need to have the talk-and, sadly, it’s usually the girl who wants it-it’s because you’re not feeling secure and/or it’s not meant to be.”

That’s exactly what happened to me when I brought up the topic of “us” to a guy I was dating earlier this year, which prompted him to launch into the spiel. “Dating is not really a priority for me right now,” he said, when I subtly asked him if he saw any potential with us, after about four months of seeing each other on and off, the last of which I was doing most of the asking out. “I’m lazy about relationships.” “Lazy” meaning not “interested.” It’s not like I was going straight for the exclusivity clause-remember, I’m a recovering CP-but I also didn’t want to continue wasting my time if things weren’t going to ever progress. Needless to say, we stopped seeing each other after that night.

Morrie, 32, single and out there dating, says that commitment doesn’t necessarily come with sex, but it’s the frequency that should have something to do it. “I’ve always believed you can’t assume just because you’re sleeping with someone that makes you exclusive,” he says. “I think the talk needs to happen when the sex and sleepovers are more than once a week and moving into the multiple sleepovers where things are being left behind, like tooth brushes, makeup, razors, bunion cream (yes, a lot of women I go out with have bunions). Of course, if you’re feeling ‘it’ and think that you don’t want to see anyone else, and you definitely know you don’t want the other person seeing anyone else, then you may need to accelerate your schedule.”

“It all comes down to a gut feeling,” says 33-year-old Sharla, married. “If you don’t want to see anyone else, then why not throw it out there? If the guy or girl flips out…it’s not meant to be. I don’t mean to be overly Zen about it, but what better way to stop wasting time?” I obviously couldn’t agree more.

Then I got this piece of advice from another newlywed. “If it was a relationship where I was just casually dating/sleeping with the guy, I would have a conversation that we could date other people but if either of us slept with anyone else we would have to tell each other,” 32-year-old Mary says. “Though, I didn’t always live up to my end of the bargain.”

So I guess it all comes down to trusting your instincts. What’s your take? Is there ever a right time for the talk, or should the subject of commitment go unspoken?

Last Girl Standing is trading in her Lollapalooza shoes for lingerie and heading to L.A. this weekend for the Midsummer Night’s Dream party at the Playboy Mansion. Check back Tuesday for her next post.