We're all looking for that sweep-me-off-my-feet-I-just- met-my-soul-mate instant click -- or at least some butterflies, right? That initial physical attraction is what gets our attention about a guy in the first place.

At the same time, there's this idea that instant love is a sparkle and fade phenomenon -- things that burn so bright eventually burn out. So we often date "nice" guys who we're just not hot for and hope that, as long as we're compatible in other ways, the spark will grow. Good idea, right?

Nope -- at least not according to Dr. Carol Cassell, author of "Put Passion First."

"For most people, attractions do not grow," she says. "In fact, research finds that the opposite is true. It's more likely that you start out with sexual chemistry and then it fades, not vice versa."

In other words, while your relationship's got to have some actual foundation in friendship for when the fire dies down, you're still better off starting off in lust than trying to fake sexual chemistry.

Tell us! Have ever felt an electric connection with a guy -- and did it last? Have you ever started off feeling "eh" about a guy and growing lustier over time?

--Reporting by Jennifer S and Shilpa Prabhakar