Why does it seem like guys go for younger girls?

Guys will chase whatever appears healthy. Beauty is health. Health signals reproductive fitness.

this is a subject of a simple but long drawn out conversation, but it basically boils down to basic biology and the lizard part of your brain understands what I just said. Why do you have crushes? For the same reasons we do. On younger men? Probably not until you're in your twenties. Right now, your age is looking for older men for experience, guidance and excitement.

Does the guy one year behind you in school turn you on? Or are you looking at last year's graduates as the "hotties" that occupy your own imagination? See what I mean?

There's a certain symmetry to the dance. Ponder for yourself why female primates reach sexual maturity two-three years before the same age males do. When you were going through puberty, who were you dreaming about?

simply put.attractiveness.

but there is also power, control, deviant behavior, forbidden lust.