7 Answers

Can't eat, can't sleep, staring without moving your eye lids: These are effects of cystal meth.

It just feels so right!

You will know .When it "hits you.Cant sleep cant eat minds all over the place.when you look into each others eyes you "stare without MOVING YOUR EYE LIDS .THAT"S what feels like. As the song says When I fall in "Love" keep dreaming 

As sweet as my blood sugar!

That person is constantly on your mind and your feeling and view of the of the world changes drastically, way for the better. You feel you can conquer anything with this energy and hopefulness! Everything feels freer and lighter................

You want to be with that person all the time and forever.  If they love you, then they will feel the same way.

If it is reciprocal:   complete-ment

If it isn't reciprocal: agony