What: Try me! I could never explain LOVE! Especially since it's a very dynamic idea or a deep emotion. It is deep and shallow at the same time, too difficult yet too easy to perceive. It just happens.. whereas other feelings I've perceived required a reason.
DO Anything: If you're the loved one, may be you may not do anything but if you're in love (living/non-living) it is quite easy to convince yourselves to do just about anything under the sun for your love, even if it appears impractical to others.
Eternal: Depends on your quantification of "Eternal". For some eternal is until lovers and/or loved ones are alive, for some others eternal is through the many lives (purportedly) one takes until one reaches Nirvana.
Now that I'm totally involved (& intoxicated) - let us discuss Afterlife & Nirvana!!