I think looks are pretty important.... How can you have a relationship with someone without finding them attractive? There would be no passion.
I don't mean they have to be model hot or someone who EVERYONE would consider attractive. But I have to find them attractive. They have to look good to me, or I won't want to touch them or kiss them. And without that, all you have is a friendship.
That said, I've dated guys before that not everyone would consider really good-looking. But I found them very attractive. It's more about the personal perception of looks than what the general population would think.
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