The only thing I'm against is what a public stance it's become. Such things should be private, regardless of if it's hetero or homosexual. Why this country has made it such a big deal to support something that's private I don't know. Every time I see a straight person rainbow-ize their facebook picture, it sounds the same to me as a white person making sure you hear that they have black friends. Good for you, and the fact that you feel like you have to tell everybody just means you care more about how people view yourself then what you're actually supporting. You can support in silence, and you can vote for anything that helps equality without telling everybody what a good job you did.
I wish we could get past this "I support this/that" thing and just be people, without the dividing lines. When you draw a circle around a certain group of people to support them for a certain reason, that's just another way to segregate them. Sure it sounds positive on the surface, but you've still isolated a group of people based on some reason that shouldn't matter in 2016. One could argue that with no support things would be even worse which may be true, but there has to be a happy medium somewhere.