That's a hard question to answer! I've been in true deep love a few times. One was love at first sight but most of them took some time to really know it was love.
Not sure I can describe it well but some of the basic feelings are a knot in the stomach, heart beating extra fast, the urge to grin all the time. I think about the person I'm in love with through out much of the day. I want to know more about him, find out what he likes and doesn't like, learn his history. I want to buy him little presents, make him laugh, make him happy.
I've known my current boyfriend for 45+ years. We have always liked each other, had the hots for each other in high school but never got together, have bumped into each other over the years. Then a few years ago we would run into each other often and talked more and more. He asked for my number one day and then sent a text to me from his dog Zoey. It was too cute. We went out never really thinking it would be anything more than just the friendship it had always been but at some point it just sparked and turned into much more.