Love at first sight?
Yes, men think so...or is it 'lust' at first sight? How can a woman or man 'really' know? If a woman thinks it is 'love at first sight', she may have found an incredibly 'hot' guy who matches her ideal social persona 'catch'. If this guy actually knows how to be a natural, all women will want him and she will have to fight with others to 'keep him' (I can teach you to be this man).
Otherwise most of them appear to be quite boring because they try to impress her and don't 'get it'. But when dealing with 'love at first sight', yes it might be, but then longer term dynamics start to sink in and kind of spoil it.
Beauty is in the eye of the beerholder, I mean, beholder. 'Love at first sight' is usually only perceptionally based if not in its entirety. No one can match up ideally to one person's expectation of who they are or who they should be. Once you find out more about them, you're going to be disappointed in what you thought they were. See how selfish we as people really are?!
Eventually you go through the hardships of a 'real' relationship and very very rarely will everything work out perfectly where the people are a real match (at least in our highly developed, opinionated, individualistic cultural society).