I KNOW there that "love at first sight" is possible but it is exceedingly rare and I think only a few people ever experience it.
Years ago I knew a lady who talked about her deceased husband in a way that was 'different' and I felt there must have been something very special there, something unusual. More than 10 years later, almost 20 years ago now, I UNDERSTOOD what it was when it happened to me - it was one of the most profound experiences of my life!
I was at a gathering in a public park when someone came over the hill and when I first saw her, a voice in the back of my head said "Your life has just changed!" I KNEW there was a connection there; I just didn't know what! She came right through the crowd of people, straight up to me (ignoring everyone else) and said "Hi!". I realized I knew everything there was to know about her (except the mundane things like her name, where she lived, etc.) and she knew everything there was to know about me, my likes, dislikes, hopes, fears, all my secrets and all the things I had never said to anyone! I can not explain the connection but it wasn't "of this time and space", it was as if the connection had always existed although we just met, like it had been there for hundreds of years. She instantly became my BFF and everyone could sense the connection between us even if we were on opposite sides of the room, a little awkward since we were both married at the time LOL! (She died from a brain tumour 3 years later but somewhere, sometime I know our paths will cross again.)