This is not really offtopic, but I didnt want to post it in dating forum because people usually talk about their problems there. So here's a great website explaining all factors of love, what causes it, why it happens and etc. I sort of found it helpful.
What its saying is love is an addicting drug just like smoking or any other. Except it doesnt influence you in a bad way. (Only sometimes I guess)
Basically, it explains why sex is important to love someone. Without sex, theres no love. And no I'm not thinking with my penis, its based on research and research! Maybe teens cannot stay together for a long time because theres no sex? Without sex theres no attachment, which is long term commitment. Sometimes people can, sometimes they cant.
If you have passionate love, with too many emotions I guess? It will be gone soon, and attachment will be gone. Divorce I guess.
[url]http://people.howstuffworks.com/love.htm[/url]
Its also a great site, it explains how things work - anything you want to know. From electronics to feelings like love or economy or government. Whatever.
P.S. Now I know what people are talking about if theres any chemistry between two people...They mean it, its just not a saying lol.