Heather wants a serious relationship with a guy who cannot commit. It seems obvious not to waste one's time over someone who doesn't give enough of his, but she is not alone in her pursuit of an unavailable love.

For me, it was Chris. He was taken when I met him, but I couldn't help but want him. (Or was it I didn't want to help it?)

Of course, he didn't mind obliging my infatuation, giving me just enough of his time that it almost felt like he wasn't taken.

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Like many people out there, I understand the appeal of a good challenge. It's fun to have that sense of chase at the start, gives me something to work for, and makes it seem like more of an accomplishment when I get him.

But if he is someone I can never get due to marriage, another relationship, or some other stumbling block, what's the point? And would I really want him once he became available?

Joanna thinks we're looking for validation when we go for the seemingly unavailable.

"How cool are you if you can get some man to overcome something -- other relationship, fears -- to want to be with you?" she said.

But that's just about insecurity. It may be an ego boost to obtain someone who seems out of reach, but it is even more rewarding to find someone interesting who wants to be with you.

With confidence, you see that you are worth being chased, even if the one you want but can't have seems so "right" for you.

While another commitment can keep a prospect off the available list, there are also people who are there but not emotionally there.

My friend Mary is a victim of the emotionally unavailable man, who shows interest but is not willing to let himself go all the way. He tells her she's the best he's ever met, but where is he when Saturday night rolls around?

SURVEY Is unavailable attractive? Yes. I always want what I can't have. There's just something sexy about married people. No. It's not worth my time. Results | Disclaimer

It's not just a male thing though. My friend Greg thinks women can be just as unavailable, playing a guy's emotions without committing. He dated one woman who would back off when things got a little tough. Someone who is there for just the good times is not someone to keep around.

When I ask others why they put up with someone unavailable, most say they can't help but like the person and hold onto the hope that things will change. Maybe you can't stop being attracted, but you can stop pursuing a relationship with someone who doesn't give you what you need. And if you make a habit of only seeking what you can't have, you're setting yourself up for unneeded pain.

After some time, I grew tired of waiting for Mr. Unavailable. It's just a constant rejection. It was hard to admit that if he really loved me, he would be with me. But that's exactly it, harsh as it may sound.

He couldn't give me what I wanted, and that's where our story ended, finally.

The thrill of the chase is fun, but not worth it if you are disregarding available lovers for unavailable ones.

Sometimes it's best to cut your losses and free yourself for someone who wants you without the "but."

Laura Lewis is an adventurous 20-something who knows how to make the most of being single. Her column appears every other Thursday.