Love at first sight or nothing else?

So I was sort of seeing this guy for the past six months or so and something just wasn't right. He wouldn't fully commit to the relationship. Finally he came clean and simply said "I don't have the same feelings for you that you have for me."

All of us have been there and that led me thinking about relationships. This person was hurt before and if the stars didn't align just right there was no hope. I've seen that when men get hurt the first few times, they tend to hold all future relationships or potential relationships responsible for their past hurts. Women on the other hand seem to be more forgiving. They will let a man cheat on them and still take them back.

Okay, before you all get your feathers ruffled...I'm generalizing and I know that ALL men are not horrible, neither are ALL women desperate.

Does love at first sight have to happen before you acquire feelings for another person? I admit that at first glance, he was nothing I would ever seek out. He's older, damaged, of average intellect and a wide range of things that would normally send me walking on a different path. But then we started handing out, having conversation and laughing together. It turns out his exterior may not have been what I sought, but internally - mentally he was damn near perfect.

I am no prize, but then again, I'm in no contest. I think people should only live in the moment and enjoy it for what it is and not try being psychic and need to know where a relationship is going. You may just be surprised where things can go when you live in the moment.

Questions:

Does love at first sight have to be present in order to have a good relationship?

Should people hold future relationships accountable for their past mistakes?

Does lightning strike in the same place more than once?

Have we moved into the age where just like technology, if you don't get it right off the bat, you give up? what happened to getting/growing to know someone entirely before passing judgement?

Why do men give up so easily?

Why do women keep trying?