A very bad topic.

Well to say the very least the so called love is a complex set of emotions. And these emotions like every other emotions wont be the same for each individual. But we could genralize to an extent. Most of the feeling are necessary for the survival. To make lasting bonding between individual or individuals or even with ideas to create a stronger system. As percieved by the individual.
Ofcourse there is a some amount of attraction when opposite sex is involved. But it is not eveything. There will also be an ought to feeling. This feeling is partial reflection of the interest you have in yourselve. And then there might be myriad other emotions to a lesser extent.