Try comparing heterosexuality to alcoholism, as a difficult thing to fight but bad for you. Consider dealing with people who treat your marriage as at best the unfortunate effect of your disease, and having to defend yourself and explain, over and over, that you've tried being homosexual and can't manage it.

I'm not suggesting that heterosexuality is a disease, or a weakness that you should be trying to overcome. Rather, that exercise might give you some idea of why this analogy bothers people, and why we feel neither comforted nor supported by the suggestion that the reason we haven't become heterosexual is because it's difficult and we don't have a 12-step program.