I also have a six yr old and definitely have noticed an increase in 'crush' behavior after she watches certain television shows or movies - there is kissing (or suggestions of it) and romance in nearly every Disney movie and on just about every one of the pre-teen shows on Nick and Disney channels that she loves to watch.
I'll be interested to read what any other mamas advise here.
I don't think we should force our kids off the t.v., but I think we should offer them other alternatives for their entertainment - sports, dance, self-defense, church, collecting, girl/boy scouts, yardwork, housework, even non-suggestive video games just to name a few things that can take their minds off of such things.
Also, our daughter has older sibs (in their 20s) who are openly affectionate with their boyfriend/girlfriend in front of everyone :-P and every time she's around them this triggers that behavior as well.
I have told her that it's okay to have a crush on someone, but at six yrs old, she can only have 'friends' - and when she is older she will have a boyfriend and later a husband etc ... when she starts talking about 'I'm in love with so&so, or going to marry this one or that someone is a hottie'... I just remind her that this person is a friend, and that we treat friends with respect.
I have talked with her very specifically about how friends act together (they don't touch) except for a high-five, and they don't hug or kiss because you could get the flu - which is the truth. Does this stop the hugging? no - but at least I can correct her if I observe or learn about it because we've already established that it's not right.
I was talking with my 6yo's teacher recently and she commented that her class this year (1st graders) were quite 'touchy-feely', more-so than usual.... go figure.
It IS a phase - your little guy is a romantic, it's just part of his personality (way better than being a bully or painfully shy).
:-)