Assumed Process of How People Start Loving Other People

I don’t really understand how people start loving certain people. Out of a blue. Like you talk to them everyday, more than everyday. Its normal. Its pretty.
And one day you wake up and realise you love them. Sometimes its not even in the morning, in the comfort of your blanketed bed. You wake up at a lone desk, or in the middle of canteen surrounded by euphoric people, or in the library stack halls, or a place that is tranquil, or in the difficult seats of metro.
You wake up.
From whatever you’ve been thinking. From whatever’s been going around. To realise you’d rather be here with them than in your head, than in your own world.
Just like that. No tantalizing little moments leading you up that stage.
Its the air that you breathe with them. It must be something in that air, I suppose. That you want them to breathe with you. Together.
I still don’t get how. But I guess when you love someone, you don’t want to know the 'how’.