You wont find a simple answer to this thing. Its just how the society work and its not just males but even girls tells me that they didnt want to see guys kissing either. It might seem to be a stereotype but in hollywood in movies or tv you might see more of them over there compared to rest of USA so they're just little more comfortable there. So Im sure they heard all kinds of crap all the time so they're just wiser not to go through the troubles.
I remember back in high school 1 dude almost kissed me out of blue and my ex-gf pushed him off and yelled him off while im still processing wtf happened in my head.
