That is a different kind of problem, though. Those couples already know who they want to sleep with, but they might be having anxiety issues or physical issues. Homosexuals often do know, most of my gay friends have slept with people of the opposite sex and know that they feel nothing when they do so, it is only through sex with members of the same sex that they feel love and excitement. Homosexual desire develops in the same way as heterosexual desire, though many don't even know it until they're older. There is nothing wrong in finding happiness in this way, because you are not hurting anyone else.
The treatment of pedophilia and erectile dysfunction are quite different. In the case of pedophilia you can often help the person cope with their thoughts and abstain from committing the acts, but you often cannot completely eradicate the desire. It is just something that needs to be dealt with because it has serious consequences; if it did not, then I am sure we would not treat it in the same way. With erectile dysfunction it is a physical ailment, which is caused by different circumstances and treated in a different way.