IS this a real question? I notice on your profile, this is your first question.... ??? And you have no "responses."
Anyway,
They do this... at certain ages.
ALL normal.
Don't worry.
They like girls.
Then find them icky.
They like girls,
then find them icky.
Same for girls: they like boys and have them as friends. Then don't like them and find them icky. And so forth and on and on and on.
It can also be just what his peers are doing... thus, birds of a feather type thing.
And OH GOSH! Don't even worry, that this portends him hating girls the rest of his life! That is not logical linear thinking, at all.
;)