I think you can go into a rapid virtuous (?) circle on first sight of someone. If you are ready for a relationship and someone appeals, you notice they are attractive and reinforce that feeling, quickly.
Aye feeling change. If the relationship is a 'goer' the lust portion of your love may diminish over time, but the friend portion part grows in proportion.
I don`t believe in love at first sight. Attraction, lust, infatuation call it what you like but love takes time. I managed it in about three days though.
But, like other posters so far, I believe in "instant attraction".
I met my OH in a crowded, noisy bar, on a skiing holiday. Hardly conducive to romance. But we kept catching each other's eyes as we tried to furtively glance over at each other.
I believe in love at first sight, the first one was a really something, unfortunately for me he was gay. I'd just pushed my tongue back off my chin when his bf came in the shop to give him a cuddle. The second was when I saw mr ask. I knew I would marry him. I think it was lust at first sight.
The moment I first saw Mrs MM I wanted to marry her. I got a mutual friend to introduce us. We have been married now for 32 years. So yes I do believe in love at first sight.
Ski-ing is quite lethal for instant romance, particularly with a few black runs and strong drinks behind one. For love at first sight, it was a girl who shared a desk at primary school and quite unrequited.
Gosh, I've gone all teary eyed! Brought back the first time I saw my husband (Fresher's Week, me 18 year old goth, him 28 year old ex-army officer, argued ferociously for six months, been together 23 years).