Guys who are not interested in a girl?

what I can't understand

if guy has no interested in girl that he does not know make no sense

why would he dislike if her does not know her

that makes no sense

why would guy have no interested in girl he doesn't know he does not make effort to know this how he know he will like her ?

that very confusing .

it has always being my problem with me it ben of my life empty lonely life it makes no sence .