When I was traveling in India I was tempted to buy everything I saw because it was so cheap and I was in a really thin phase. My friend Jessica did her best to stop me from going nuts at a particularly alluring bazaar in Udaipur. Her motto: “Make sure it passes the zip code test.”

Like shopping, dating outside your zip code should be done with caution. If a sari, or a girlfriend, wouldn’t look right at home, you probably shouldn’t commit. When you’re trying something—or someone—on for size, you have to envision what it or she will feel like on your couch, at a party with your friends, at dinner with your parents. That’s why it’s usually best to shop close to home.

I spent my junior year of college “studying” abroad in Sydney. That meant I took classes in photography and Buddhism, jogged on beautiful beaches and dated an Australian guy named Andrew. I wanted to stay in Sydney with him forever. My parents talked me out of it, largely by threatening to cut me off if I didn’t catch a flight home. Andrew and I continued to date long distance when I got back to college at Cornell. This was pre-Skype, and I ran up an insane phone bill even though I could never keep track of the time difference. Still, we excitedly planned his visit. I couldn’t wait for him to meet my friends and family.

Of course, it didn’t go as planned. My parents were freaked out that he was 10 years older than I was and lived on the other side of the world. My friends thought he was kind of an asshole because, well, he kind of was. I remember walking with him through campus and feeling as if I was hosting an alien. It wasn’t just that his jeans were weird or that he couldn’t handle the cold. It was that I suddenly felt we had nothing genuine in common now that he was in my zip code.

When Andrew and I were in Sydney, we treasured every moment together, all too aware of the clock loudly ticking in our ears. Our relationship was dramatic and destined for failure. It was exciting—until the reality of the vast distance between us set in.

Sure, some people end up happily married to foreigners. More often it doesn’t work out. Happy people are usually in rational matches with people who have similar upbringings and values. Sometimes we date the opposite of that because we’re not ready for the real thing.

I have two friends who recently got divorced from foreigners because their mates ended up feeling isolated living far from home. At first their exoticness was sexy, but it became a liability, particularly when children got involved.

Dating someone who lives in a different city, much less a different country, is rarely sustainable. Much of your time is spent acting as if you’re on vacation, because you usually are, meeting somewhere for a fun trip, when everyone is on their best behavior. Real relationships don’t usually come with maid service. They often involve laptops in bed and brunch with parents.

A New Yorker friend of mine recently broke up with a guy who lives in England. Although they love each other, neither was willing to move to the other’s turf. It’s hard for adults to leave behind the life they’ve been leading for decades—unless they have no life, and why would you want to date that person? When they were still together, I watched this poor Brit get stuck grilling at a barbecue while his girlfriend had fun. Only a polite tourist would make that mistake.

Another friend shacked up at the Chateau Marmont with her foreign boyfriend when he visited her in Los Angeles, even though she owns a home there. She thought it would be fun and sexy, and it was—until he returned home and stopped returning her calls. The physical distance between them is too vast for her to figure out what went wrong.

Even a local commute can sap the fun out of a new relationship. A friend of mine recently started dating a divorced guy with two kids. “It’s not the kids who are the problem,” she said. “It’s that he lives in Venice.” She was referring to the Westside of L.A., about a 45-minute drive from her house in the Valley when there’s no traffic, which is almost never. She’s making it work, but it’s not ideal. It helps that their offices are in the same area—if you’re not walking in on them when they’re making out on a couch.

When I first moved to L.A. I also lived in Venice. I loved the cool beach community and was convinced I’d never date a guy who lived anywhere else. Despite my intention, I ended up seriously dating someone on the wrong side of town. I was always in traffic, wearing the wrong shoes. Forgetting my computer charger at home would kill a day. Six months later I moved in with him. I realized I couldn’t juggle a commute and a boyfriend.

Around that time I got a call from Andrew the Australian. He was going to Las Vegas for a big event and invited me to meet him there. I said I had a boyfriend, and Andrew insisted we both come meet him. We could take in a show and a fancy dinner!

I doubt he really thought it would happen. The fantasy was fun while it lasted, though, just like our romance abroad. And just like the black and gold sari that lives in my closet.