Well alot of people (much less so today) winced at sexual minorities getting married because they thought it would redefine the concept of marriage; that being between a man and a woman. The truth is, straight people ALREADY redefined what marriage was through the ages. It is now the legal union of two autonomous and equal individuals... that's it.
As for the 'fear' that the gay married couple down the road may affect a straight person's marriage, yeah... how?
"Oh darling, those two men are so in love down the street, it's hard to get an erection in these conditions. Oh how I hate love when it doesn't conform to the parameters with which I'm comfortable with."
"Oh absolutely darling, tea?"