A lot of guys do like younger women, especially older guys, sometimes because it is reaffirming to their sense of virility and sometimes for purely physical reasons.
Other times, it's just a simple case where you can't control who you fall in love with.
Now, if you want to get me started on a whole different tangent, then we could discuss the biological implications of why men are attracted to younger women, why women are attracted to tall, strong men (bet you didn't know that it was because of your DNA, did you?
), why men are attracted to women of certain body types, etc.? i have never been attracted to guys around my age because they were never mature and acted like children.
My mom is only 4 years older than him so looking at that perspective I don't know. Not all guys that are older than the female are total pervs though some are, just like not all young women are immature, some are more mature for their age.