Myself, used believe in Love at first sight. Happened fall in love with that gal few years ago. Cannot resist on her for unknown reason. Just feel hunches about her. Feel like I know her for many years but just met her recently. Turned out she and I have some conficts over some issues, personality, and communication. But one question is how can she and I fall in love each other with too many mismatch. Just supect something with spirt or karmic progression.
After she gone, I start careful with anyone. If i feel vibes about someone I happen fall in love, then have to be patience to get know that person more better before go ahead too far. Not want to repeat mistake.
For me, I rather "Love at second or third sight" for more safe than being sorry.