Why is this going on in The US?

because people are stupid and are brainwashed by super right-wing or religious narrow-minded morons to think that being gay is somehow wrong and practically a disease. these people ignore all kinds of reason (like the studies showing that ity might be genetic) and instead have to react so negatively and violently to something they're not used to. it's just like all the violent acts white people used to (and unfortunately sometimes still do) commit against minorites. trust me i'm white and i live in texas so i know these people. ugh.