When it comes to dating, they say there are plenty of fish in the sea. But what do you do when you want the catch your friend threw back? Many people think there's an unwritten rule that you just don't date a friend's ex, no matter what the circumstances. But if you're really crushing, it can be hard to ignore your feelings.

Trey, 15, had a serious thing for his best friend Rico's girlfriend from day one. He'd always had trouble talking to girls, but Kelly was different. She was smart, funny, and they had a lot of things in common. But when Rico and Kelly broke up, Trey knew he had to keep his distance to save his friendship.

"It was hard not seeing Kelly anymore, but it wouldn't have played out any other way," he says. "Rob and I had been friends forever, so I guess I made a choice."

Don't Go There?

Carol Weston, author of For Teens Only and Girltalk, says it's really common to have a crush on someone your friend once cared about. "You've probably already gotten to know the person, and maybe you've already done a little 'safe' flirting," she says. "At least your friend can't accuse you of having terrible taste!"

Maybe so, but should you even go there? Any way you slice it, romancing a friend's ex is touchy — and some people just won't do it. "No way," says Sarah, 16. "Even if your friend did the dumping, it's just not cool to go after her ex. Out of respect for your friendship, you should leave it alone."

Proceed With Caution

If you can't walk away from your feelings, be prepared for a little drama — or maybe a lot of drama. Dating a friend's ex can work, but it doesn't come without a price. "Proceed with caution," warns Weston, especially if your friend's nursing a broken heart. "If you date that person, your friend will suffer more, and your best-friendship will be at risk."

For Miriam, age 17, getting together with her best friend's ex was worth the risk — even though it added friction to the friendship. Miriam tried to keep the relationship under raps at first to protect her best friend Erica's feelings, but when Erica found out about it, she felt really betrayed. "I felt like I wasn't good enough for him, and that he'd chosen Miriam over me. I just felt really low," says Erica. "Their secrecy was all done to protect me, but I just felt like Loserville: Population, one."

It was hard for Erica to see them together, and she suggested that she and Miriam should "see other friends" — meaning, not hang out anymore, at least for a while. "I seriously thought about breaking it off with Seth," says Miriam. "Erica was my best friend, and the idea of not speaking to her anymore was horrible. Eventually, I broke up with him, and soon after that, Erica and I were tight again. It was like it never even happened."

Do Damage Control

Weston points out that friendships can often be based on deeper, longer-lasting connections than some romantic relationships, so ask yourself how important the friendship is to you before risking it all. If you decide to go for it, try asking your friend for the go-ahead. You might say something like, "Our friendship is important to me, so I wanted you to know that Tyler and I would like to start seeing each other. I hope that wouldn't make things awkward between us." Your friend might get upset — maybe a little, maybe a lot — but if you're upfront about your feelings, there's probably a better chance of salvaging the friendship in the end.

Miriam and Seth recently started dating again. But this time, Miriam called Erica first to ask if it would be OK. "I thought that was the sweetest thing ever," says Erica, who swears there are no more hard feelings. "I just want them both to be happy, and I think they really are."