Okay, I'm back to the poor arguments that people use. First, let's go to arguments from the church and its members.
They argue that gay marriage is wrong because it doesn't lead to children or eternal families. But I know people who can't have children, yet their marriage is supported by the church -- they are even sealed in the temple. Also, I know a man who is married to a widow who was sealed to her first husband. They cannot, therefore be sealed in the temple. Their marriage cannot lead to an eternal family. But the church seems to be okay with their marriage. So the arguments against gay marriage don't really hold up in general.
Then we have the arguments in support of gay marriage. There is a general feeling that we can't expect people to be chaste; that marriage is primarily based on mutual attraction; and that marriage is primarily for the benefit of adults, while children have little to do with it. These arguments aren't really new with gay marriage, but they stem from the "free love" movement that pervades western media driven culture. And I feel the arguments are wrongheaded.
It's hard for me to get behind a side in an argument when these kinds of faulty reasoning are used. I don't want my support for the church to be linked to the poor arguments. I don't want my support for gay marriage to link me to the arguments typically used to support it. It's problematic.